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Fitbit Sense Review: Healthcare via your smartwatch

Proactive. Thanks to ECG, heart rate, SpO2 and temperature sensors, Fitbit Sense currently is one of the most advanced wearables in terms of health monitoring. We have taken a close look at this smartwatch and its health functions in our review.

Fitbit Sense
1.40 inch, 336 x 336 pixel 339 PPI, Full touch, AMOLED, glossy: yes
Audio Connections: ⊕, NFC, Brightness Sensor, Sensors: Gyroscope, altimeter, 3-axis accelerometer, skin temperature sensor, multi-path optical heart rate sensor, multipurpose electrical sensors compatible with ECG app & EDA app
802.11 b/g/n (b/g/n = Wi-Fi 4/), Bluetooth 5.0 LE, GPS
height x width x depth (in mm): 12.35 x 40.48 x 40.48 ( = 0.49 x 1.59 x 1.59 in)
Operating System
Fitbit OS
Additional features
Speakers: ⊕, Keyboard: 1 button, Keyboard Light: yes, Fitbit Sense, classic wristband (small & large), charging cable , Fitbit, 24 Months Warranty, GPS, GLONASS; compatibility: Android 7.0+, iOS 12.2+; water resistance: 5 ATM, waterproof
33.5 g ( = 1.18 oz / 0.07 pounds) ( = 0 oz / 0 pounds)
329 Euro
Note: The manufacturer may use components from different suppliers including display panels, drives or memory sticks with similar specifications.


Case and Connectivity

The smartwatches Fitbit Sense, Versa 3 and its predecessor, the Versa 2 (still available), all from Fitbit, have very similar dimensions. Instead of the mechanical button of the Versa 2, the Sense and Versa 3 watches are now equipped with a sensor button that is integrated into the aluminum case, similar to the Charge 4. The Versa 3 also has GPS. Another difference is that only the Sense and Versa 3 will be equipped with Google Assistant by the end of the year while the Versa 2 will not.     

All three wearables measure the heart rate and oxygen levels in the blood (SpO2). Only the Sense has additional sensors with which it can assess ECG and electrodermal activity (EDA). It also has a sensor that measures skin temperature.

Voice Assistant, Fitbit Pay

Other hardware include a speaker, a microphone, a voice assistant and NFC for mobile payment. You will have to check whether your bank supports Fitbit Pay. Alternatively, Fitbit also offers its own Fitbit Visa Card.    

Amazon Alexa currently functions as the voice assistant for Fitbit smartwatches. However, Google purchased Fitbit about a year ago and has now announced to make Google Assistant available for Fitbit Sense and Versa 3 by the end of the year. We do not yet know whether users will be able to choose between Google and Alexa or if Google will be removing Alexa from the smartwatches in the long term.

The voice assistant only works when the user's smartphone is nearby. The app does not need to be open, but it needs to be allowed to run in the background. Unlike Versa 2, Versa 3 and Sense now also feature a speaker. While Alexa continues to display answers on the screen, we expect Google Assistant to answer via audio. 

Setup and Handling

As soon as the Sense is recharged, it is ready to use and starts counting steps, tracking workouts and doing an EDA scan, which we will talk about more later on. You can connect the smartwatch to the Fitbit app from the App store or from Google's Play store. 

The Fitbit app also lets you equip the Sense with additional apps such as Strava and Uber as well as additional watch dials. Some of these include their own design for the Always On screen, others don't. In this case, users can choose between a standard analogue or a digital watch face.  

Installed apps
Installed apps
App store
App store

The sensor key that Fitbit has been using instead of a mechanical button since the Charge 4 takes a bit of getting used to. It is positioned in a hollow below the display and is more difficult to reach than a normal button. Depending on whether you press it once, twice, or press and hold, the smartwatch either goes back a step, starts an assigned app such as the music player or opens a selection with four favorite apps.

Notifications, widgets and quick settings such as the Do Not Disturb mode can be accessed via gestures. The same goes for the other apps which users can list according to their preference.

Weather app
Weather app
Today dashboard
Today dashboard

Telephony and Notifications

The Sense signals incoming calls and can accept or decline them. Users will still need the phone for the call itself.

Notifications remain visible until they are deleted or marked as read. You can answer WhatsApp messages with an emoji, a preset answer or via voice message. This all worked well in our test but requires your smartphone to be nearby and allow background activity for the Fitbit app.

Users can connect their Spotify or Deezer accounts to the Fitbit, although this only works with premium accounts. While the Sense can only be used to access the Spotify playlist on the phone, Deezer actually loads playlists onto the smartwatch, which can then be listened to directly from there via a headset or another Bluetooth receiver (offline). 

The Sense could be a bit faster occasionally. For example, you have to wait a good 5 seconds before anything happens when opening the Today dashboard that displays the daily sleep and activity data.

Health and Fitness

Fitbit introduced active zone minutes with the Charge 4 back in spring. This is based on a new evaluation of all daily activities. Intensive activities such as cardio or high performance activities now have a higher count than less intensive activities (fat burning zone). But in the end, every activity counts. The Sense recognizes and counts a fast-paced walk without users having to activate a training session. This automatic tracking increases the daily active zone minutes quickly and motivates you to move.   

Health monitoring

The Sense monitors the user's heart rate 24/7 and emits warnings when limits are exceeded or dropped below, according to Fitbit. We checked the precision of the device's heart rate sensor by comparing it to a chest strap from Polar. There weren't any major differences between the two results. The heart rate sensor remained accurate within 1-3 beats compared to the belt in our test with an increased heart rate, which we simulated in performance mode. Those are promising results.

The Fitbit Sense logs changes to skin temperature and can also create an ECG (electrocardiogram). Fitbit received the EU's CE certification (Conformité Européenne), which is important for medical devices, in September. To do an ECG, you have to place your index finger and thumb on the stainless steel ring around the display for 30 seconds. If the Sense recognizes any heart rhythm irregularities, this could indicate atrial fibrillation, which doctors connect to an increased risk of stroke. 

Another feature is the EDA scan, which detects electrodermal activity of the skin. If the Sense registers changes in the skin's electrical conductivity during a 2-minute scan, this can indicate emotional stress. The test is conducted at rest, which in itself can reduce the heart rate. This effect can be enhanced with relaxation exercises through Sense and the Fitbit app.

EDA scan
EDA scan

Sleep monitoring

The hemoglobin in our red blood cells plays an important role in supplying our body with oxygen. The oxygen level in our blood stream (SpO2) indicates, to what percentage the hemoglobin in the lung is filled with oxygen. This value usually lies between 90 and 100 percent.   

Fitbit doesn't measure this saturation manually at the press of a button, like the Huawei Watch Fit oder Honor Watch ES do. Instead, it is active during the night while you sleep.

The oxygen saturation curve in the sleep protocol doesn't just show the trend of proportional saturation, it also indicates the deviation from your own body's average. High deviations could indicate sleep apnea. The paid Fitbit Premium subscription also gives you access to the heart rate trend. Neither the app nor the Today dashboard displays the actual proportional saturation. At least the SpO2 watch dial displays your average. This is based on the measurements of the previous night and doesn't change during the day.

The Fitbit Premium monthly subscription costs around $10 and offers premium functions. The sleep protocol, for example, is complemented with a heart rate diagram. The following screens display the sleep protocol without a subscription. The four screens below show the same sleep protocol with a premium subscription. Except for the estimated oxygen deviation, all diagrams can be opened to full screen on the smartphone.

Buyers of the Fitbit Sense can trial the premium subscription for free for six months. Apart from the additional diagrams in the sleep protocol, the subscription features additional health metrics about the development of oxygen saturation at night, the breathing rate, the heart rate variability and skin temperature. The subscription also allows users to participate in virtual competitions and create plans for health-related and athletic goals.

Premium users can request a health report in PDF format after about a month. This can be printed and used to discuss any questions or issues with your doctor. It includes the dashboard trends for rest frequency, sleep scores and weight, the trend of daily steps, active minutes and inactive minutes (sitting) as well as active zone minutes. Women can also see their menstruation cycle, if they track this manually in the app.

If you log in to with your account data, you can also download your data as an excel or CSV file, even without having a premium subscription - although this format is a lot less easy to read. 

The following screens on the left show the daily dashboard. The health metrics are only visible for subscribers.

Daily dashboard (1/2)
Daily dashboard (1/2)
Daily dashboard (2/2)
Daily dashboard (2/2)
Health metrics (1/2)
Health metrics (1/2)
Health metrics (2/2)
Health metrics (2/2)


The Sense also has an app named "Coach" that features guided cardio and body workouts. Short video clips instruct the user what to do. At the start of the test there were three workouts available that ranged from between 7 and 15 minutes. The premium subscription offers a wider range of workouts.

The normal training app lists 20 training modes including running, bicycling, using the cross trainer as well as kickboxing, playing golf and doing interval training. 

You can personalize the trainings screen and set parameters such as track length for swim training or the number of repetitions, training duration, length of breaks and total duration of an interval training. The Sense vibrates differently when reaching the fat burning, cardo or high performance level, which is useful if you want to run within a certain heart rate range, for example. The Always On mode reduces the refresh rate but always displays the training screen. 

The sensor key pauses and restarts the workout while pressing a softkey on the display ends the workout. This worked well in our review, even with sweaty fingers, although the sensor key is more difficult to find and activate that the mechanical button is on the Versa 2. The Sense will only show you a summary of your workout right after it ends. After that, you will only be able to see your training metrics in the app. 

Battery Life

Fitbit claims that the battery of the Sense lasts up to 6 days if you turn off the Always On feature. If this feature is activated, the battery life reduces significantly. It lasted about three and a half days during testing.

The Fitbit Sense only takes 1.25 hours to recharge thanks to its quick charge function.

If you are looking for a smartwatch with an ECG function, the Fitbit sense is currently one of the only options. Another one is the Apple Watch. While Samsung announced an ECG sensor back in 2019, the manufacturer keeps pushing back its release date again and again. The Galaxy Watch 3 is supposed to be launched in March 2021 (in Germany).    

The health monitoring features are very good in this Fitbit Sense smartwatch. 

However, there are some details missing from the analyses. For example, the smartwatch doesn't provide concrete data on skin temperature and the oxygen levels in your blood. Fitbit works with tracking the course and noting deviations to indicate health disorders. This might be enough and will prevent sensitive people from worrying about individual lower values or the comparison to body temperature, but it also means that the data cannot be validated, which is a shame. Similarly, SpO2 cannot be measured during the day, which would be a nice feature to have available, at least manually.

We also miss the option of being able to call up data from at least the previous training after a workout. The Sense smartwatch also does not provide information on VO2max and therefore doesn't analyze the training benefits nor provide recommendations for the period of recovery before the next workout. We really would have expected the latter from a health watch. We were pleased with the possibility of adapting the device to various kinds of sport, including training screens, and by the reliable measurement of the heart rate.  

The Sense is the only watch that also includes ECG, an EDA scan and a temperature fluctuation monitor. The cheaper Versa 3 and Charge 4 smartwatches also support the division of daily activities into active zone minutes, the informative dashboard and the normal sleep protocol. Fitbit Premium can be tested for free on other wearables as well. Fitbit has recently extended the trial period to 90 days.     

Price comparison

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> Expert Reviews and News on Laptops, Smartphones and Tech Innovations > Reviews > Fitbit Sense Review: Healthcare via your smartwatch
Inge Schwabe, 2020-11- 3 (Update: 2020-11- 3)