Fitbit Surge, activity monitor with GPS | Full analysis

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The Fitbit Surge, announced along with the Charge and Charge HR, es el primer reloj GPS de la compañía de Silicon Valley. Típicamente relacionada con los monitores de actividad, supone su primer acercamiento a los relojes deportivos más específicos. Aunque no podemos considerarlo como «un reloj para correr», ya que ni siquiera Fitbit lo hace – en su publicidad el eslogan usado es «super reloj de forma física» – el poder mostrar ritmos y distancias de forma más precisa nos puede hacer pensar que lo sea. Pero quizá lo que más destaca de Surge es su sensor de pulso óptico, que permite obtener datos de frecuencia cardíaca no sólo durante las actividades y entrenamientos, sino también a lo largo de tu día a día.

As always, I like you to know the origin of the test units. This review is to be thanked to Fitbit because, as in the case of Charge HR, han cedido un Surge para la prueba y análisis. Y ahora ya puedo confirmar que ambas unidades se volverán con ellos tan pronto como pulse el botón de «publicar». Como ves, total transparencia.

If you like the work I do, and thanks to this test you are encouraged to buy a Fitbit Surge, do it through the links I provideThis way you can help the site without it costing you a single penny. What's more, the offers I put up usually allow you to save good money, which is good for everyone!

And after all these details have been cleared up, let's get on with the analysis of the Fitbit Surge.


The presentation of the Fitbit Surge is very careful, with an impressive looking case. On the front you can find a photo of the watch as well as an indication of the three functions that Fitbit wants to give more presence to: GPS reception, pulse sensor and notification reception.

Fitbit Surge

En el lateral de la caja puedes ver cómo se hace referencia al tipo de producto ante el que nos encontramos. No es un reloj destinado a los corredores, es un «super reloj de forma física». Así que de esa forma debemos tratarlo.

Fitbit Surge

La caja ni se desliza ni se extrae, se abre. Como estás viendo la presentación está muy cuidada y seguro que la caja de marras vale «una pasta». Y eso que esta es una versión descafeinada, pues al ser una unidad de prensa parece que la caja no está completa. En esta parte interna los productos definitivos tienen un texto motivador que no tiene la unidad recibida.

Fitbit Surge

But let's stop admiring the packaging and let's get the contents out because in the end that's what matters, and the box will go in a drawer at best.

I have not yet been able to remove the watch from the case, which is still attached to another plastic holder, but this is what you will find inside the case. In addition to the Fitbit Surge you will find the charging cable with USB connection (only for charging, not for synchronization), a USB dongle and a small instruction manual.

Fitbit Surge

After releasing the watch from its last support, I can now turn it on, and so start getting to know each other. The Surge strap is made of an elastomer material, a type of flexible plastic. Once on the wrist it is comfortable and light. The touch screen is black and white and has a size of 20.88×24.36mm, it also has automatic lighting.

You can find three buttons to control it. The left button will be used to enter the main menu (and if pressed twice, to activate Bluetooth music control) or to return to the previous menu, if you have entered any sub-menu. The lower right button will advance through the menus and the upper right button is limited to certain options such as ending the activity, working only when there is a prompt next to it.

Fitbit Surge

En la parte trasera se encuentra el puerto de carga y «la joya de la corona», el sensor de pulso óptico, exactamente igual al que encontramos en la pulsera Fitbit Charge HRDespite the fact that the charging port has no protection, the watch is submersible up to 50m, although Fitbit recommends not to use it in the pool or shower. But I have the impression that the reason for the warning is more to avoid possible skin irritation problems that some users complained about in the Fitbit Force. That is, despite the recommendation, it will stand up perfectly to your shower or swimming with it, although in contact with water the screen will stop working properly.

Fitbit Surge

This is the sensor that Surge uses, surrounded by two green LEDs that will flash insistently and throughout the day (although if you are bothered, you can deactivate it from the menu). And next to it, the connected charging cable.

Fitbit Surge

Finally, the wireless Bluetooth adapter. It is a Bluetooth Smart adapter, but it is only used for synchronizing the watch with the computer, you will not be able to use it to connect to other devices (mouse, keyboard, phone, etc.). And since the vast majority of you will be synchronizing with your mobile phone, the best thing you can do is put it back in place with the instruction manual, because after reading this test you will not need it either.Fitbit Charge HR

We load the watch, put away everything that doesn't serve us, and go to training.

Activity monitor

The activity monitor in the Fitbit Surge is exactly the same as the one in the rest of the Fitbit range, with the advantage of having a larger screen where data can be consulted more easily.

The activity and the calories consumed are calculated by taking three values: Steps walked, floors climbed and heart rate (which determines the intensity of the exercise). And these data are obtained by the accelerometer, the barometric altimeter and the optical pulse sensor respectively, all of them integrated in the watch itself. It is the algorithms used by Fitbit which, starting from all these data together with those introduced in the initial configuration (mainly weight and height), finally estimate the calories consumed and the distance travelled.

All this data appears directly on the Fitbit Surge screen without having to access any menu. And you can move between the different screens simply by sliding your finger over the display. The screens you can access are steps, heart rate, distance, calories and number of floors climbed.

The activity recorded during the day will be continuously synchronized with the phone, and you can access the application to check the updated data at any time, as well as from your computer on the Fitbit website (www.fitbit.comThis application is available for Android, iOS and Windows Phone.

This is where you will find all the data on your activity, both daily and from your training for running and other sports.

Fitbit Surge - App

By clicking on each of the different lines that appear in that image, you can enter the complete graph of those metrics. By default, the development of the last week appears, but you can change the view to months or years, depending on how you want to see the data.

On the website you will find the same information, but represented somewhat differently.

Fitbit Surge - Web panel

By clicking on any of the sections you will access the complete information, for that day or for a specific period.

Fitbit Surge - Extended tile

What you must take into account, not only in the case of the Fitbit Surge activity monitor, but in all activity monitors, is that the number of steps indicated is not an exact value. In the end, everything depends on the calibration of the accelerometer, and it is not always possible to distinguish a step from a hand gesture, or to interpret that you are walking despite not moving your arms, such as pushing a baby carriage.

This value should therefore be used as a reference, and if the daily goal you have set is 12,000 steps, you know that if it marks 12,500 you may have taken those steps or stayed at 11,950, but your activity has been high. And if on the other hand it is marking 4,000 steps, it is because this day you have been especially lazy and you still have time to go for a walk and meet your goal.

When validating the data provided, I can compare them with data collected by other activity monitors on different days, taking as an example the comparison between the Fitbit Surge on a doll and a Garmin Fenix 3 in the other.

Fitbit Surge - Activity monitor comparison Fitbit Surge - Activity monitor comparison Fitbit Surge - Activity monitor comparison

You can see in the three comparisons that the number of steps differs from one to the other, however the distance data is similar, as well as the activity graphs. These are the values that you must analyze, beyond an exact figure, you must confirm that your activity has been elevated throughout the day.

Sleep monitor

Cuando ya has acabado tu día y has estado plenamente activo y cumpliendo el objetivo marcado, no te quites tu Fitbit Surge, porque es el momento en el que va a monitorizar tu sueño. El cambio de modo entre monitorizar la actividad y el sueño es totalmente automático y funciona a nivel de servidor. Es decir, se sincronizan todos los datos y cuando la información está en los ordenadores de Fitbit, son sus algoritmos los que dividen tu actividad para determinar cuándo has dejado de estar «en este mundo» y estás roncando plácidamente en tu cama.

When you wake up the next day, you can check how you slept that night. And of course, thanks to the pulse sensor, you can also check your pulse during the night.

Fitbit Surge - Pulse during the night

The most detailed is the quality of your sleep, as well as indicating the time you fell asleep and the time you woke up.

Fitbit Surge - Sleep Analysis

The automatic recording it makes is really good. The truth is that, compared to other manufacturers, Fitbit has one more variable to calculate, which is the pulse. When your body enters the state of deep sleep the pulse drops dramatically, which allows you to identify perfectly when you are really asleep, and not only from the movements of the wrist.

Although generally speaking I have found data that can be confirmed as true with other activity monitors, sometimes they have not interpreted well the fact of simply lying in bed watching TV or working with a computer. Fitbit solves it in a much easier way in the case of the Surge (and also in the case of Charge HR) precisely because of its pulse sensor.

Not only is it important to be precise when establishing what your effective sleep hours have been, but also the amount of data you can provide about how effective that rest time has been, a point where Fitbit stands out positively, both in the data you can find on the web panel and in the mobile application. And at least it helps me to know that I don't really get enough sleep.

Fitbit Surge - Sleep for a month

Los datos que puedes encontrar en la aplicación móvil y en la web son, en esencia, los mismos. Pero es que es en la «app» donde mejor análisis podrás realizar y donde encontrarás todo más ordenado.

24 hour heart rate monitoring

Just like the bracelet Fitbit Charge HR, el Fitbit Surge ofrece un seguimiento de tu frecuencia cardíaca durante todo el día, gracias a su sensor de pulso óptico que usa «fotopletismografía». Así es como se denomina este tipo de tecnología, más fácil de explicar que de memorizar el nombre. El sensor de pulso está flanqueado por dos LED de color verde. Éstos iluminan la piel, permitiendo al sensor medir los cambios en absorción de la luz. Y son de color verde porque el color rojo absorbe al verde.

Therefore, in each cardiac cycle (each pulse), blood will pass through veins and capillaries that as you know are red (now I wonder... will this technology work with the aristocracy?) and what the sensor measures is the variation between reflected and absorbed light. That way it is able to give you the pulse data.

Well, after this kind of anatomy we can now talk about the Fitbit Surge and its constant heart rate monitoring. On the clock you can see your current pulse at all times. It's as simple as scrolling through the screens left or right to the one that corresponds to your pulse.

Fitbit Surge - Pulse

This data is stored and synchronised with the application on your phone (or when synchronising with your computer, if you don't have the app installed on your phone), and you can access it for later analysis.

Fitbit Surge - Heart rate

En la lista de días, podrás acceder a cada uno de ellos para entrar en la información más detallada para ese día concreto, pudiendo identificar patrones y momentos del día de mayor actividad (o inactividad). También tendrás la información de tu ritmo cardíaco en reposo, así como las zonas de frecuencia cardíaca que tu cuerpo «ha visitado» y durante cuánto tiempo.

Fitbit Surge - Heart rate

The resting heart rate is not the lowest rate. You can see in the picture above how my resting rate for that day has been 50 beats per minute, but while I have been sleeping it was much lower, around 40 beats. So the resting pulse is not the lowest pulse your heart can reach, but the average resulting from the data taken while you are not active, i.e. sitting, sleeping or just not moving.

What about accuracy? On all trial days of both Fitbit Surge and Fitbit Charge HR I haven't seen anything strange in the graphs. There are no sudden spikes that can't be caused by intense activity, and at the time of some activity the pulses go accordingly.

Running with Fitbit Surge (using GPS)

The essence of Fitbit Charge HR and Fitbit Surge are the same. They're both good activity monitors, plus they offer constant monitoring of your heart rate. But when we go for a run, that's where the second one comes in.

Starting the activity simply requires using the left button on the clock to access the main menu. Here, we can select the race option.

Fitbit Surge - Career

You can make your selection by clicking on the confirmation button (the bottom right button, where it is marked on the screen) or by pressing on the center of the screen. Then you will have two options for running using the GPS. The first one is Free Run.

Fitbit Surge - Free run

But we also have another way, interval running

Fitbit Surge - Race intervals

I will start with the first one, as it will be the most common use for the vast majority. After selecting the type of race we are going to make, the search for satellites begins.

Fitbit Surge - Satellite search

After finding satellites, the main screen is presented. There are no data screens as such, but a screen with two fixed fields (the upper and the central one) that indicate total distance and travel time. The lower field is the one that allows you to rotate between the different information options offered, which are the following

  • Rhythm
  • Average pace
  • Heart rate
  • Calories
  • Steps
  • Clock

So there are eight fields available in total (the 2 fixed ones plus the 6 you will rotate through). You can access these metrics by simply moving your finger or tapping on the screen.

This is the basic training function, but if you go back a few lines you will remember that I have talked about interval racing. The basic operation is the same, but in this mode the upper right button is enabled so you can mark laps manually (instead of laps per kilometer).

In this mode what you see on the screen will change a little. Distance and elapsed time will no longer appear on the screen as in free run mode, but will be replaced by lap number and lap time respectively.

Fitbit Surge - Race intervals

The last line is still available to show different metrics, which this time will be the following:

  • Back rhythm
  • Distance returned
  • Rhythm
  • Heart rate
  • Distance
  • Elapsed time
  • Clock

As you can see, the interval race is configured for those days when you have to do series. However, it is not possible to schedule training sessions of any kind that will mark different phases or go through them in succession.

In the case of the interval race, when you mark a lap you will be shown a screen with the specific data for that lap.

Fitbit Surge - Lap Marking

This information is not displayed when you complete a kilometer in free run mode, as is usual with watches of any other brand, but then that kilometer separation will appear in the application when all the data is synchronized.

Fitbit Surge - Activity

You can pause the activity at any time by pressing the same button you started with (the lower left button). And you have two options, to resume the training by pressing the same button, or to end it with the upper right button.

Fitbit Surge - Slow activity

When you finish the activity you will have the summary of your training with the main data of your training. If you have done an interval training, first you can check the times in each of the laps you have marked.

Fitbit Surge - Summary of laps

After this screen (and in case the training is free running, it goes directly without the lap details), the data displayed are the typical ones like time, distance or average pace.

Fitbit Surge - Summary of activity

In addition to these, there are others that we do not usually see, such as the steps (which are added to your daily activity to reach your goal) or the meters of accumulated unevenness.

Fitbit Surge - Summary of activity

And when you get close to your phone again, if you don't have it with you, your activity will be synchronized and you can check data such as rhythm, heart rate or calories on the Fitbit website.

Fitbit Surge - Activity

And of course, of course, in the mobile application as well.

A very practical feature is that if you are doing interval training you can select whether you want to see the manually set times or the automatically set lap times per kilometre.

Fitbit Surge - Manual Laps

The application makes good use of the phone's screen, as it offers the information in differentiated tabs and at a fairly generous size.


The cycling option is something that was not integrated into the Fitbit Surge from the beginning. It is a separate application from the running one for two reasons. The first and most obvious is because in cycling we don't show the pace, but normally we will prefer the speed. Secondly and more importantly because the Surge, in its running profile, needs to have a running cadence for the correct calculation of the pace (if there is no cadence the pace it sets is 0). This was solved by adding the cycling exercise profile.

The Fitbit Surge has no support for any kind of external sensor, so you can't pair it with a specific speed and/or cadence sensor, let alone a power meter.

You should also note that if you want to have heart rate data, you will not be able to put the watch on the handlebars, for obvious reasons.

As for the data fields, they vary from the race profile, not only because now the rhythm is not shown, but also because what is most missing is the instantaneous speed information. That's right, this data is not available, and what is shown is the average speed. In a sense it makes a little bit of sense, since you are not going to wear the watch on the handlebars but on your wrist, so you are not going to use it as a cycling computer.

The fixed data on the screen are the same, distance and activity time, and the ones you can select in the lower band are the following:

  • Average speed
  • Heart rate
  • Calories
  • Clock

As you can see, the cycling profile is quite basic. It is valid if you want to count your cycling trips, but it will not be useful if you like cycling a little more seriously.

Other sports

Con el Fitbit Surge no nos vamos a limitar simplemente a realizar el registro de entrenamientos de carrera o de ciclismo gracias al GPS, también podrás usarlo para actividades más genéricas, como entrenamiento de pesas, yoga o pilates. Todas ellas se encuentran englobadas dentro del menú «Ejercicio»

Fitbit Surge - Exercise

These activities can be the ones that are configured by default (image on the left) or choose one of the ones that you can select additionally (image on the right).

Estos modos no ofrecen configuraciones muy especiales, es simplemente una forma de permitir que a la hora de sincronizar una actividad aparezca con el nombre apropiado, para poder hacer el seguimiento correcto. Así que, en vez de sincronizar dos actividades con el nombre «ejercicio» que luego no sabrás qué son cada uno, te permite identificarlas claramente y saber cuándo ha sido una clase de pilates o de spinning la actividad que has creado.

When it comes to viewing the activities, there is nothing specific about them, and a gym session will show the same information as a spinning session (including steps, something a bit absurd...).

Adicionalmente, en el menú de carrera puedes encontrar otra actividad, llamada «Carrera en cinta». Te permite hacer un seguimiento más o menos preciso de ritmos y distancias cuando corres en interior, tomando datos del acelerómetro interno.

Fitbit Surge - Race on tape

Unlike other models on the market, the Fitbit Surge does not have automatic calibration when we run outdoors, but sets a default step length depending on your height, but we can calibrate it manually. For this purpose Fitbit has a guide on how to do itAlthough instead of doing the procedure indicated by Fitbit (not everyone has an athletic track handy), simply take some of your past running activities using GPS, as you'll have an approximate distance measured by GPS and the total number of steps.

After making the division, simply enter the resulting data in the user configuration, and you can go on the tape.

Fitbit Surge - Stride Configuration

The accuracy of the results, therefore, depends on the data you enter for the stride measurement. Although this will depend on each individual user and their usual rhythms, as well as the rhythm used on the treadmill, because normally the stride size for warm-up rhythms of 5:30min/km differs from the stride when you are running at 4:00min/km. Therefore you always have to count on a percentage of error, whatever value you enter, it will never be totally accurate.

Optical heart rate sensor

Fitbit has equipped the Surge with an optical pulse sensor, but it is not the typical Mio/Philips sensor (like the one that equips Mio Link or TomTom CardioThere is no information on who is in charge of the manufacturing, nor of the tests behind it.

There is no doubt that one of the most important selling points of the Surge is the pulse sensor integrated into the watch itself. But what we have to demand from this sensor is that it has the correct precision for high intensity exercise, that is, that it goes beyond the correct detection of the pulse at rest or moderate activity, which is what we can ask from the Fitbit Charge HR.

Fitbit Surge is a watch that has a running mode and an interval running mode, so the precision it offers in both modes must be more than correct, its performance must be flawless.

As far as resting pulse monitoring is concerned, we have seen before that we cannot put any constraints on it. It works correctly, recording all the data continuously and without showing readings that we could ever think were not correct. But we still have to see how it behaves during our sporting activities.

Para ello he seleccionado diferentes entrenamientos que he realizado durante estas semanas, y los he comparado con un sensor de pulso pectoral, tecnología que ya sabemos que, aunque incómoda, no presenta mayores problemas más allá de no haber humedecido lo suficiente los «pads» de la cinta de pecho.

First of all, this training lasts about 1 hour, at a stable pace, and the only thing to note is the peak in which the pulse decays rapidly due to stopping to drink water. This point serves perfectly to establish a point where we can fix ourselves.

Fitbit Surge - Pulse graph comparison

Comparing the two graphs, you can see how, except for the first section where it seems that the Fitbit graph makes a strange (surely it can be explained by a bad placement, and an adjustment of the strap, it usually happens to me when I go out to run), both graphs overlap perfectly, at least at the beginning of the training. But as the training passes, the graphs are separated, although the readings are very similar. Therefore you can see how the Fitbit is recording the data with some delay.

Fitbit Surge - Pulse graph comparison

The second example is a 10 km workout, also at a constant pace. This time there are no stops of any kind.

Fitbit Surge - Pulse graph comparison

But let's compare both graphs, which is where we can best check the results. This time there are hardly any problems. They do not overlap at 100%, but it is enough to have started recording one clock 1 second earlier than the other for the slight difference, but in this case the reading is totally correct.

Fitbit Surge - Pulse graph comparison

But where the problems come is when it comes to making series or intervals. Here we find the Achilles tendon of the Surge optical sensor. If in the continuous readings more or less behaves reasonably, in the rapid changes of rhythm is where it gets lost. In the first comparison, in the first and third interval you can see how a stranger does, lowering the pulse reading when I'm just starting to make the interval. From there, instead of being at the same point as the chest sensor, we see again how the graph has some delay.

Fitbit Surge - Interval Pulse

Two more intervals of that same workout, where again we see how the Fitbit Surge reading is always lagging behind the reading taken with the Garmin Fenix 3 and the chest pulse sensor. And, again, a complicated start in the second interval, lagging far behind the time when the interval starts.

However, when the time comes to cool down, there are no more problems here and the two graphs overlap perfectly.

Fitbit Surge - Interval Pulse

As you can see, the Fitbit sensor is not up to what can be demanded of it when we train in a demanding way. This data can be valid for an activity monitor, where our workouts are mostly going to be more relaxed or without so much demand in terms of data accuracy. But as soon as we ask for more, we find the limitations.

Therefore, if you are interested in having a reliable monitoring of your heart activity during your exercise, it is difficult to recommend the Fitbit Surge for this task. If this detail is not that important to you or you are not going to do interval training, then the Fitbit Surge may be sufficient for your use.

As to whether Fitbit can solve this by means of an update, although I think it's complicated, it's feasible. In short, the sensor is working correctly and is able to read the pulse achieved. It's already a simple matter of adjusting the algorithm used and the data acquisition speed.

GPS Reception

When we start an activity, the first thing we have to do is wait for the Fitbit Surge to search for satellites. And at this point it does not stand out especially, as it does not have satellite searches. Therefore, every time we start an activity, especially if we start at a different point than where we finished the previous one, we will have to wait a little longer than usual than with any other watch launched on the market in the last year or year and a half.

It's not that it's too long or excessive, it's just that being used to finding a satellite signal in a matter of 15 seconds, the Surge can take a little longer, but there's nothing better than showing you a video where you can check it out first hand.

This search is conducted two days after the last training, and 40 kilometers away, with a full view of the sky without buildings or trees that could be a problem.

But the most important thing is the stability of the pace shown, and how fast it is reflecting our speed changes. The latter is crucial, especially on days when we have a series training planned, especially if they are intense and short fartleks. And just like in the search for satellites, I have also recorded a video for you to check.

The Surge is quick to vary the rhythms, however, as Suunto does, the rhythm is filtered along with the cadence. This Suunto calls it FusedSpeed, present for example in the Suunto Ambit3.

As you have seen in the video, the instantaneous pace is shown in multiples of 5. So you will see your running times go from 4:10 to 4:15 for example, but not in between. However, you can select an average lap time (in interval racing) and those times will go to the second. Obviously when you finish your training the average pace will include those seconds in between (4:12 for example). In this aspect it behaves like the vast majority of new watches of other brands, only Polar keeps an instantaneous pace to the second.

As for the distances, I have been compiling them in a table for later comparison. These days of tests I am beginning to recover from an injury, so there have not been days of long runs, which is where the greatest differences may exist. However, at all times the distances are very close to those recorded by the other watch I always wore to training, a Garmin Fenix 3.

 Fitbit SurgeGarmin Fenix 3
Tuesday night training6.79 km6.81 km
Bicycle return from swimming pool3.1 km3.07 km
Cycling to pool6.35 km6.28 km
Water Race5.45 km5.2 km
Tests and photos Fitbit Charge HR6.45 km6.64 km
Wednesday night training7.93 km8.07 km
Recovery start training6.22 km6.17 km
Post Injury Test4.01 km4.04 km
Cloudy Thursday night9.17 km9.32 km

Especially curious is the day of the Carrera de las Aguas, which officially had a distance of 6.1 km. Neither of the two is close to that figure, which is normal because of the difficulty of the test (most of the test takes place in the streets of a village, very narrow and with houses of 2 or 3 floors, very bad areas to have visibility of the sky), but both mark quite similar distances.

The figures are within the normal, in addition neither of the two is clearly marking greater or lesser distance than the other, but alternating in the possible failure. It is normal, because we must also take into account that they were carried in different wrist and this affects more than it seems, not only in terms of signal reception possibilities, but in terms of radius in curves and turns.

Recording tracks

Recording tracks I have seen a curious case, and that is that, as with the heart rate data, there is a slight delay in making the recording, for example, the data from this cycling activity.

Según la gráfica de Garmin, la rotonda la tome a 25,3 km/h. Y tomo esta rotonda como ejemplo claro de saber a qué velocidad iba. Más que nada, porque entré bastante pasado, ya que es una rotonda en bajada cuya salida se cierra, y tuve que frenar bastante fuerte para no hacerla «por encima». Esos 25 km/h me parece que concuerdan bastante con la velocidad que podía llevar en ese momento dentro de la rotonda.

Fitbit Surge - Compare GPS data in cycling

The problem is that, according to the graph obtained with the Fitbit Surge, at that precise moment it says it was running at 39km/h. It can be seen at the point marked on the roundabout and on the line on the graph.

Fitbit Surge - Compare GPS data in cycling

Furthermore, you can see how this point on the graph would correspond almost to the fastest point for this section, and after this point it decreases considerably. Being the exit of the roundabout, it is clear that the braking takes place before entering, and not when exiting.

That is, the speed data does not match the GPS position data, there is a time lag of seconds. For the vast majority this will not be a major detail, but if you like to analyze cycling trips or passing speeds at certain points, it can be quite uncomfortable.

Battery life

If you check the specifications that Fitbit gives for the Surge in terms of battery life, the only thing you will find is the following message:

Battery life: up to 7 days

But there is no further indication of whether it is with or without GPS use, or with or without a pulse check, so there is not much data to hold on to in order to quickly assess the Surge's range.

As far as using activity monitor and recording some activities with GPS, along with constant synchronization with the phone (i.e. regular use), Fitbit makes it easy for me, since it regularly sends you emails (and warns you with messages in the application) of different events such as distances, activity summaries, medals for completing goals, etc. And among them it also sends another one when the battery is about to run out, so that will be the reference I use.

Here's an image of the time between two warnings. I simply let the battery level be too low before I put the Fitbit Surge back on, to let its battery run almost empty again.

Fitbit Surge - Autonomy

In the end, it also depends a lot on how many activities with GPS use you do, because it is what consumes more, but just over 7 days is a very good result for a device that, I remind you, is reading heart rate data during all this time, in addition to recording activities with GPS use (in that period of time, about 3 hours in total).

And what about the autonomy with the use of GPS? Because nowhere in the specifications do we find information about this. The only detail I could find is what Fitbit sends in the same battery warning email, which states the following:

Under normal use, the battery should last up to 7 days. A fully charged Surge device can monitor up to 5 hours of activities that require the use of GPS. Happy trails!

Well, someone should check the contents of that email, because with the battery fully charged I started a cycling activity, which uses GPS and pulse sensor, and the duration has exceeded 11 hours. For this I just left the clock in the window on the roof, and I picked it up the next day.

Fitbit Surge - GPS Autonomy

Actually, I think it's excessive, especially considering the specifications that Fitbit gives, so I propose to do another test where I can constantly check the clock to see if it's recording the activity with the screen off or if there's something that doesn't match the normal use of the Surge.

For that I wait for a suitable opportunity, like the one last SaturdayI left the house at 8 a.m. and started an activity marked as cycling. After finding a GPS signal the day went on normally. I was going to be outdoors all morning, so it was a perfect opportunity to do the test.

At lunchtime he was still recording the activity, at which point I lost sight of him and when I got home he was obviously off. So after loading the clock and synchronizing it, I look at the result again on the web. And again it's more than 11 hours that he's been recording the activity.

Fitbit Surge - Autonomy

But something doesn't add up, because if I started recording around 8 in the morning and arrived well before 7 in the evening, something doesn't add up here. And indeed, after reviewing the heart rate graph and going from a distance graph to a time graph, I seem to have died at some point in the afternoon, because the heart rate changes to a completely straight line.

Fitbit Surge - Autonomy

In fact, the clock is not reaching 11 hours that it seemed to be reaching, but it is well over the 5 hours indicated by Fitbit. From the position of the graph I calculate that it will go through the 9 effective hours of autonomy, which without being the 11 hours I had been surprised with, is also a very good result.

What I suppose happens is that the clock marks in the file the end of the recording when the clock is put in charge and is turned on again. In both occasions it has coincided to have done it around 11 hours after starting the activity, which has helped the possible confusion. But thanks to the pulse graph and to the fact that I am not dead, it has been easy to find out how far the battery has gone.


The lighting options of the Fitbit Surge differ from what we are used to seeing in other watches. What is most missing is that there is no option to keep the screen always on, something that those of us who run around at night on a regular basis consider almost mandatory. Within the menu we find three different settings for the screen lighting.

Fitbit Surge - Lighting configuration

  • Auto (default option): The Fitbit Surge has an ambient light sensor (which can be seen in the frame of the screen) thanks to which the screen will light up automatically, if the ambient light is low, when the screen is used or a button is pressed
  • On: The screen lights up whenever a button is pressed or the screen is touched
  • Off: The display is not illuminated at any time

The addition of the illumination sensor is a good thing, but we still need an option that allows us to keep the screen on. When we run at night and we need to see some data on the screen, we must press it or press a button. We can use the left menu button, because within the activity it has no use of any kind and will allow us to illuminate the screen, because if you touch it you will most likely change the lower metric.

Fitbit Surge - Lighting

The lighting offered is not excessively intense, but it is more than enough to consult the data while we are running.

Use as a diary clock

First and foremost, the Fitbit Surge is designed to be the watch you wear every day, both for performance as an activity monitor and for heart rate monitoring. So Fitbit has made a special effort to make the wearing experience as a watch as complete as possible.

To begin with, there are several clock displays to choose from, all of which are quite aesthetically pleasing.

Fitbit Surge - Clock face configuration

De entre todas ellas la que más destaca es la de «Flare» pues las líneas que hay en la esfera que rodea la hora es el indicador de cuál ha sido tu actividad minuto a minuto. Como se puede ver en la imagen, no ha habido actividad hasta cerca de las 5 de la tarde, y así es como se muestra en la pantalla y como lo puedes identificar de forma rápida.

Fitbit Surge - Flare

As with the Flare clock screen, there is a lower line on the keystroke screen that represents the intensity of activity over the most recent period of time, and if your keystrokes are currently in any of the areas defined through the application (automatically or manually), it will also be represented accordingly.

Fitbit Surge - Widget pulses

Pero no es la única pantalla «inteligente». El widget de pasos también tiene una línea que se irá completando a medida que vayas llegando a tu objetivo marcado para el día.

Fitbit Surge - Widget steps


Fitbit Surge allows you to create multiple silent alarms, in which the warning will be through the vibration of the clock (there is no other way, since Surge does not have audible warnings). These alarms are not configured from the clock, but must be established from the application to synchronize later. However, it allows you to create a multitude of alarms, in addition to establishing a repeat on the days you want (for example, to wake you up on weekdays).

Fitbit Surge - Alarm settings

As I said, it is not possible to create the alarms from the clock, but it is possible to activate or deactivate them from the clock. Fortunately, once synchronized, we do not need the phone to disconnect them.

Fitbit Surge - Alarm settings


So if your phone runs out of battery on a Friday night and you've forgotten to turn off the alarm for tomorrow, don't worry, turn it off directly on the clock.


Fitbit announces that the Surge is capable of showing on-screen notifications, but I find the implementation very poor. Unlike other clocks, the Surge doesn't show notification of everything that appears in the mobile panel, but will only notify you of incoming calls and received SMS messages (and with a somewhat strange behavior, at least in Android). No notifications for applications like Twitter, Facebook or WhatsApp.

Fitbit Surge - Call Notification

I don't know about you, but I haven't received any non-advertising SMS messages in a long time, and the number of calls per day is also quite small. Besides, when the call appears on the screen (at least in Android), it can take up to 2 seconds to show the notification, that is, in that time until the clock warns you who is calling you, you have usually already picked up the phone and seen it directly on its screen.

What the Surge does offer is music control, but to do this you have to pair your watch with your phone a second time, via standard Bluetooth, which will affect the battery.

Once this new synchronization is done, you can control the music both within an activity and in the clock mode. Pressing the menu button twice will start the music control mode.

Fitbit Surge - Music Control

From here you can not select any folder or song, the controls are basic. It will allow you to pause or resume playback or go to the next song, as well as display the name of the song and the artist on the screen.

Remember that all music playback will be done by the phone, you cannot load songs into the watch or use it as a music player independently.

My opinion

Fitbit Surge

En el Fitbit Surge tengo sentimientos encontrados. Hay aspectos de él que me han gustado mucho, pero hay otros detalles que me hacen llevarme las manos a la cabeza y preguntarme «pero qué co…» (inserta aquí la interjección que te apetezca).

Starting with what I least liked, without a doubt, are the mobile notifications. I think this is an important factor in this type of devices designed to be carried around with you at all times, and it is one of the main factors that Fitbit announces for the Surge. Well, these notifications are limited exclusively to showing you who is calling you (with a certain delay in notification) and to showing you SMS messages (who is still using SMS messages today?). In short, no Twitter, Facebook, email, messaging programs... And being a company based in Silicon Valley, the cradle of technological advances in terms of mobility, I think it's pretty creaky.

Another thing that I have missed a lot is the ability to configure the data displayed during an activity. I think that the arrangement of three fields with two of them fixed is quite clever and very appropriate for a device of this type, but I would love to be the one to say which fields I want as fixed, and not have them come predefined automatically.

As for the pulse sensor, it depends a lot on the use you want to make of it. If you want to have full control of your workouts and want to follow up after the activity is over, it's easy to find its limitations. But on the other hand, for normal use (which, in the end, I think is the use that 95% will make of Fitbit Surge buyers) it's more than enough, and well above what has been offered so far in products such as Samsung or Motorola watches, aimed at the same type of audience.

I think the mobile application is fantastic. In both iOS and Android it is simple, very graphic and fast to use. However, the web portal is a bit more chaotic and slow, although most of the time it will be on the mobile where we consult all the information.

In short, I think that the Fitbit Surge has a complicated situation in the market. Not because it is a bad product, but because it is halfway between different types of users. Whoever is looking for a watch to run and it is imperative that it has the pulse sensor integrated into the watch itself has better options with more specific products, such as the TomTom Cardio and in a short time the Garmin Forerunner 225And whoever wants a device to control different sports activities but without the desire to compete, for about 100 euros less can get a Fitbit Charge HRIt's not that I don't recommend the Surge, but I think that among running watches there are much better options, and as an activity monitor there are cheaper options.

As Fitbit's first device with GPS, I think it's enough, but I'm looking forward to seeing how far they can go. They offer a very fresh view of the sector, and I think they can bring a lot of new ideas to the table. But some effort with the Surge would be welcome, especially in the area of mobile notifications, where I think they need to improve further to match the competition. And that same development will be useful when they launch a replacement.

Did you like the test?

I hope that this test has cleared up some doubts about Fitbit Surge. The truth is that doing each test you see on this page requires many hours. Taking data, photos, videos, writing your own test... It's a long and demanding process, because I only like to offer you the best.

If you liked it and want to show your gratitude, you can leave your impressions in the comments below. It will help me to know your opinion, or to ask me questions if something is not clear to you. Share the post on social networks, I'm sure your friends will like it too.

If you want to buy the device, you can do it in the links below, so you save by getting good offers, and I get a small commission that supports this website and its tests.

Buy Fitbit Surge

You can buy Fitbit Surge in three different colors, the black one you have seen in this test and also in blue or orange. For both models there are two sizes available, S or L. Here are the links where you can buy it.

Fitbit Surge - Smartwatch, color blue, size L
Price: 182,04 €Prime
1 new from 182,04 €   0 Second hand
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Operation - 7.5
Connectivity - 8
Design, finish and comfort - 8.5
Battery life - 8
Aplicaciones - 9.5
Price - 7



User Rating: 3.65 ( 5 votes)

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  1. You don't mention how often it records the gps signal. If every 1 second as the phoenix 3 or every 4 or 5 seconds as the vivoactive (by the way, do you think that in the future you can put it to record the signal every second in the vivoactive with some update, I don't see the point)
    On the other hand the pulse sensor is not exactly the same as the FIbit charge Hr, I mean exactly the same with the same precision, or is this one more precise?
    Sabes si la toma del pulso (frecuencia cardiaca) cada cuanto la hace¿¿, lo digo porque por ejemplo se ha sabido que en Apple watch que también las toma 24 horas, la toma cada 10 segundos cuando no haces actividad y cada 1 segundo cuando se hace actividad, en este es igual, diferencia actividad intensa de de moderada para la toma frecuencia cardiaca.
    By the way, do you know if you can add a bluetooch chest band to the Apple wacth, like the h7 polar band, to improve its accuracy?
    Greetings and great work

    1. The recording is per second. The sensor used is exactly the same as the one in the Fitbit Charge HR, there are no differences between them.

      Data collection is constant, as you can see from the graphs.

      In principle you can add the external sensor, but I have not tested any unit.

      1. The vivoactive can be set to record every second, or force record every 4 or 5 seconds as you mention in your post. if this is the case, you think this will improve in a future software update or it is impossible as it is at the hardware level. A salute and keep it up, you are one of the best in analysis of these gadgets.

      2. Me autorespondo yo, la grabación no es siempre por segundo al igual que en el Apple Watch, que al segundo en actividad deportiva y cada 10 segundo en actividad normal. Según la pagina web de fitbit española la «.es» el fitbit charge Hr monitoriza la frecuencia cardiaca de la siguiente forma :

        «Guarda datos sobre el ritmo cardíaco a intervalos de un segundo durante la monitorización del ejercicio y a intervalos de cinco segundos el resto del tiempo»
        That is, every 1 second if you are exercising and every 5 if you are in normal. similar to the Apple Watch that is every 1 second in exercise and every 10 in normal. A greeting and I hope I have contributed something to that I had doubts about the matter. Great work in yours with the reports

        1. The measurement in Fitbit is constant (every 5 seconds at rest is quite frequent, as there is hardly any variation in HR). In the Apple Watch after the last update it is much more lax. During exercise it is constant throughout the session, but at rest it is every 10 minutes and only if you are not moving.

  2. Very good Edu, I own the Fitbit Charge HR and I have the option to get the Surge for 160 Euros which would already have GPS. Would you update, wait or consider other options? I have been questioned by your analysis of the Forerunner 225... Greetings!

    1. If you're happy with the Fitbit and just want a little more performance in your races, it's a good choice. But obviously, as a running watch, the 225 is a much better choice.

      In short, the Surge is a high quality activity monitor with running functions, while the 225 is a good watch for running, with a simpler activity monitor.

      If you want to lean more towards the running clock, the 225 will be a better choice. If it is for walking and fitness, the Surge offers better data.

  3. Good morning. Maybe everything I want to know is already answered, so excuse me. My idea is to use the Surge as a 24 hr heart rate monitor... I understand that without the gps the battery will last me about 7 days. On the other hand, I suppose that without hitting any button, nor putting any specific activity, I can see the real time reading of the pulse... Finally, to know if to make weights the heart rate meter fulfills its function well. Thank you very much

  4. Hello, thank you very much for the clarifications,
    Only two things, can the gps data be passed to wikiloc?. and Garmin connect along with pulse data? Thank you.
    Tengo mi garmin 310xt pero la cinta pectoral me molesta y ya de paso saber como duermo. Me llama mucho el fitbit surge . Gracias

    1. You can download the activity file and manually upload it to the platform of your choice, including pulse data, or you can automatically synchronize with Strava, for example.

      Remember to send in the vote for the Log Book Awards!

  5. Hi, everybody.
    What other alternatives would there be to Fitbit?
    I'm looking for a watch of this type for my girlfriend, since she doesn't start doing sports continuously, and with an activity monitor she might get the bug.
    What I do need is for you to have the sensor on your wrist for heart rate monitoring.

    A salute.

  6. Very good and thanks for the analysis.
    In the two images about activities (weights and spinnimg) referring to the burning of calories, the average of these are identical, having different heart rates as well as duration of the trainings, which leads me to think that it calculates it in a generic way, without taking into account heart rate nor more parameters than the generic this correct?

    1. The measurement is done from the same application of the clock (exercise), so the data is the same, the classification is done after the synchronization.

      What determines the calories is mainly the heart rate. However, keep in mind that this is not exact data, it is an estimate.

      1. Okay. And excuse me for not being clear. To him, all activities burn the same calories if you do them at the same time? Come on, the question is whether he uses pulse measurement for calorie-burn results...

        1. Keep in mind that the intensity of these two activities has been quite similar, which is why the data on calories burned are so similar, because the duration is practically the same and at a low intensity. If the exercise were of a higher intensity, those calories would increase.

          What counts is the intensity of the exercise.
          That's what the Surge takes into account.

  7. You recommend this bracelet, my sports are inline skating, walking and gym, now I'm thinking about a mountain bike, I can not run on the knee that I have operated, in gym because elliptical, spinning, body pump. What I said for what I do the recommendation?

    Greetings and thanks

    1. Yes, for that kind of use the Fitbit Surge can be perfect, since you don't need a registration or very advanced trainings. It's a perfect choice.

      1. A couple of questions, can you connect to Endomondo? and then some other device that is the same or similar to this one, is that I read that it produces allergy to quite a few people


        1. Yes, Fitbit and Endomondo can be synchronized, so after synchronizing with Fitbit's platform you will have the data in Endomondo.

          There were allergy problems with older Fitbit models, which were withdrawn at the time. None of the current models have that problem.

  8. Good Eduardo, thank you very much for your effort in analyzing. I have the hr charge and I want to prepare for a triathlon, nothing professional, it's just a hobby.

  9. Hello!! great analysis, a doubt to see if you help me, I want to buy a watch with integrated heart rate monitor and GPS, for training race, bike, paddle and sometimes swimming (for swimming I do not care that I do not serve), also for daily use type quantifiers, I do not care much that I do not give notifications of the mobile (if it brings well and if not nothing happens), which of those who have tried I would recommend regardless of price ..., the emergence is what I seem to like but I do not know other models of garmin, polar etc, thanks for your help!

    1. You can decide between the Fitbit Surge and the Garmin Vivoactive, they are the most suitable for your use

  10. Hello,

    Very complete review!

    I'm thinking about buying an activity monitor. From what I've read, the vivamart HR is the best option right now.

    However, I have seen that for a little more (70 euros) I would have a fitbit arises that already incorporates GPS.

    What would you recommend?

    Thank you!

  11. Hi, comparing the Fitbit with the A360 polar and/or the Apple Watch, what would be the order of best to worst, considering that my activities are swimming, spinning and occasional running.

    1. For swimming, neither Polar A360 nor Apple Watch will do.

      I would choose Fitbit Surge or Garmin Vivoactive HR

  12. Excellent post.
    I decided to buy the surge thanks to your detailed and exhaustive review, it is functional since I like running as a hobby and exercise indoors and that I measure my pulse every moment is excellent.
    I congratulate you on your work and for continuing to rack up the miles.

  13. I'm looking for a watch that can be used both as an activity monitor and for my workouts, my sports are mostly gym and running training (both linear and interval) and I have doubts about which one to buy and more after reading most of the analyses you've done (congratulations on them, they help a lot)

    I like the fitbit Surge, I've been watching the Polar M400 which for a price I think is quite good, and it seems that it is also valid as an activity monitor.

    Mi presupuesto es de unos 200€, ¿podrías ser tan amable de ayudarme con la elección, o recomendarme uno similar?

    1. If you are going to do gymnastics and a lot of intervals I think that the optical sensor is not the best option, a sensor in the chest will always give you better results.

      Take a look at Garmin Vivoactive, is now very well priced and it fits what you're looking for.

  14. A question, in the email warning of the battery, which holds from 28 to 5 with low battery ¿ I bought it days ago and I have it in low battery without using gps or anything. I get low battery and does not take even 2 days since I charged

    1. I don't understand what you mean about holding from the 28th to the 5th.

      The application simply sends the warning when the battery reaches a certain percentage, it's a simple reminder.

  15. Good morning:
    In the application I have installed on my iPhone, after performing an activity (hiking, for example), I cannot see the contour lines in the graph.
    I'm doing something wrong, or you don't really have that option.
    Thank you for your attention.

    1. By contour lines, do you mean the altitude? That information is only visible in the panel on the Fitbit website.

      1. Right.
        In other applications, in addition to seeing the route taken on a map, there is an option where you can see a graph with the different altitudes of the route.
        Greetings and thank you for your response.

  16. It is a clock that I have found practical and with the aids to program it useful.
    I have only found one regrettable snag in it. It is its strap which is a disaster, it has filled with empty lumps because the outer layer has come off and it is a depressing sight to wear it on your wrist. I have only had it for a few months.
    Such a good tool with a pitiful appearance.

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