The smartwatch landscape is growing more health-focused every year. ECG monitors and pulse oximeters are becoming more commonplace, and Fitbit is attempting to keep up with the crowd with its latest smartwatch, the Fitbit Sense. Fitbit’s top-tier smartwatch delivers a lot of what we’ve been asking for, and some things that still need some tweaking. Read our full Fitbit Sense review to learn more.
Update, October 2021: This Fitbit Sense review has been updated with information on the snore recognition update, as well as comparisons with the Galaxy Watch 4 and Apple Watch Series 7.
The Fitbit Sense is a major hardware upgrade over the Fitbit Versa 2. It’s made of the same materials for the most part, but just about everything else is more refined.
The stainless steel and aluminum case looks about the same as the Versa 2, but it feels significantly more well-built. Think Apple Watch-level build quality. It has a 1.58-inch AMOLED panel that’s a little rounder than that of the Versa 2. It’s a nice screen. It gets plenty bright outdoors in direct sunlight and has good viewing angles. There’s still a big ol’ bezel surrounding the display, though it’s notably smaller than the bezels on previous Fitbit watches.
The Fitbit Sense is a premium smartwatch through and through.
The physical button on the left side of the case has been replaced with an inductive button, which we’ve seen on the Fitbit Charge 3 and Charge 4. It now acts as a home button, not a back button.
I like the idea of inductive buttons, but in practice they’re not great. This one can be unresponsive at times. It’s positioned a bit too low on the case, so I’ve ended up pinching my wrist multiple times. As a result, I’ve just gotten used to swiping to go back and avoiding the home button altogether.
The Fitbit Sense comes with a new “infinity” strap, which no longer buckles like a normal watch. It instead includes an Apple Watch-like buckle. It’s fine, but boy, do I hate putting these things on.
The strap itself is very nice. It’s way softer this time around and it doesn’t collect dust or lint as quickly as others. Also, Fitbit finally fixed its horrible proprietary strap mechanism. The Sense’s straps now function like the Fitbit Charge 4’s straps: you press down on a small latch to remove them. Once the straps are locked into place, they do wiggle around a bit. If you don’t like the sport strap that’s included in the box, a variety of first- and third-party straps are available on Fitbit.com and Amazon.
Fitbit claims the Sense can last up to six days on a single charge in smartwatch mode (i.e. no GPS usage). That’s accurate as long as you watch what sensors and settings you’re switching on. I’ve been able to get about five days or so on a single charge. I’ve also been messing with the device way more than I normally would, and I’ve been going out for runs with GPS enabled. For reference, a five-mile run drained about 10% battery. You can also turn on the always-on display, though battery life will be reduced to roughly two days.
Another small-yet-notable upgrade: the Fitbit Sense has a new charger! It’s still proprietary, but Fitbit got rid of the weird clasp-dock thing. Now, it is magnetic and supports quick charging, which can charge your Sense from 10-80% in ~40 minutes.
Health and fitness tracking: Nailing the basics
Fitbit is positioning the Sense as its most health-focused wearable to date, second only to the Fitbit Versa 3. The Sense has three major advantages over the Versa 3: an EDA sensor, a medically certified ECG monitor, and a skin temperature sensor.
The Sense isn’t the first wearable to have an electrodermal activity (EDA) sensor, nor is Fitbit the first company to offer stress tracking. But most companies do so by monitoring your heart rate variability (the interval between each heartbeat).
The Fitbit Sense’s EDA sensor applies small, undetectable electrical charges to your skin to measure how they interact with your body’s sweat level. Research shows electrodermal activity is closely linked to our emotional state. I’d suggest reading this handy overview on EDA from Bryn Farnsworth if you’d like to learn more.
Taking an EDA recording is pretty simple. Open the EDA Scan app on your Fitbit Sense, then place your hand over the display. It takes two minutes to record. That might seem like a long time to sit there with your hands still, but I’ve found it helps calm me down quite a bit.
I have doubts that the EDA sensor will be the preferred method for stress tracking over heart rate variability, at least in its current implementation. EDA scan results don’t provide as much data as one would think. You’re given a small graph showing your heart rate data for the scan, as well as the number of EDA responses you experienced. In the example above, I experienced six EDA responses. The text below each graph reads “… you should typically expect fewer EDA responses the calmer you are.”
But, compared to what? Is six considered “few?” Presumably, I should be shooting for zero every time, but there was no indication that this particular scan was better or worse than my other EDA scans. There’s no “You might want to relax a little more, here are some mindfulness practices” or any other insights immediately following the measurement. More details about how this data works and what users should do with it would be very helpful.
I also felt like I received more trustworthy results from my Garmin Fenix 6 Pro compared to the Sense. I was extremely stressed one morning, so I thought it was a perfect time to test the EDA sensor. It came back with zero EDA responses. The Fenix 6 Pro showed my starting stress level was quite high, and respiration rate and heart rate data helped fill out the overall picture of my stress. Take that for what you will; I don’t have another EDA sensor to compare with the Sense.
The results from your EDA scans, as well as your responsiveness (amount of strain your body is under based on HR, HRV, and EDA data), exertion balance, and sleep quality combine to form a stress management score from 1-100. I’ve found my stress score has mostly been reflective of how I’m feeling on any particular day.
There’s also the question of how useful manual EDA recordings are compared to all-day stress tracking using heart rate variability (HRV). After all, most people (well, I’m assuming here) will only record EDA scans when they’re stressed. That means their stress scores might be affected if they aren’t recording frequently. It all depends on how Fitbit weighs EDA data against other stress inducers. By contrast, stress tracking using HRV can happen all day whether you manually record your mood or not.
Generally, I think Fitbit’s stress tracking efforts are interesting and will be more than fine for most people. After all, the overall stress score has been accurate. I just think the EDA implementation needs some refining.
In 2020, you can’t have a health-focused wearable without an electrocardiogram (ECG) monitor for detecting potential heart issues like atrial fibrillation (AFib). The ECG monitor wasn’t activated on the Sense by the time it launched, but Fitbit began rolling out ECG functionality to Fitbit Sense users in the US, UK, and Germany on October 8. My Fitbit Sense review unit here in the US received the update right away. All I needed to do was update the ECG app in the Fitbit app, and it was sent to my device right away.
The Sense’s ECG monitor is medically validated by the FDA and has CE clearance in Europe, just like the Apple Watch and (soon to be) Withings ScanWatch.
The whole process of taking an ECG reading is a little clunky. Selecting the ECG app on your watch prompts you to go to the Discover tab in the Fitbit app, then scrolling down to select an ECG document. You then need to go through a few disclaimers before you can start recording an ECG.
Once that’s done, reopen the ECG app on your Sense. Make sure you’re sitting still, then put your index finger and thumb on the Sense’s bezel. Sit there for 30 seconds, and the Sense will display your results. Well, it’ll only tell you whether it senses any signs of AFib. You need to go back into the Discover tab to see your actual ECG results. Why isn’t this available in the main Dashboard of the Fitbit app? I think Fitbit needs to do some reworking here to make the process more seamless. In addition, you can only see your actual results once you export a PDF to your internal storage. Again, I’m not sure why this isn’t available without going through extra steps, but I hope Fitbit tweaks it in the future.
As for the accuracy of the ECG results, everything matched up well with my Withings ScanWatch.
At a time when getting sick could be a very bad thing, I’m sure a lot of people will be happy to hear that the Fitbit Sense also has a new skin temperature sensor to catch early signs of illness. The sensor records the temperature of your skin at night, compares it to your personal baseline, and shows you trends over time. The graph in the Fitbit app is simple and easy to read. None of my readings ever went outside my target range throughout the Fitbit Sense review period.
It’s easy to see the value of this sensor. You wake up feeling a little off, check your Fitbit app, and it turns out you were burning up overnight. I have no doubt this type of sensor will be a mainstay on Fitbit devices going forward, and I hope others adopt it too.
Skin temperature sensors will hopefully be a mainstay on Fitbit devices going forward.
Like Fitbit smartwatches before it, the Sense will measure your blood oxygen levels with its SpO2 sensor. It’ll track your levels overnight and show you an oxygen variation graph in the morning with its findings. You’ll be able to see any high variations (or breathing disturbances) you experienced during the night, potentially warning you of more serious health conditions. However, the Sense’s SpO2 sensor is not medically validated, so it cannot categorize any of these disturbances as sleep apnea.
At launch, the Fitbit Sense’s SpO2 implementation had some major caveats — namely, blood oxygen trends were only available to Fitbit Premium subscribers. Since this metric was arguably why you’d want to use the blood oxygen sensor in the first place, this was a major oversight at launch. Thankfully, in December 2020, Fitbit allowed non-Premium subscribers to view their blood oxygen trends.
One blood oxygen annoyance is still prevalent, however. The Fitbit Sense will only record SpO2 when you’re using a certain watch face. If you’re using a watch face that doesn’t prioritize SpO2 data, you literally won’t get that data in the Fitbit app. It was likely implemented this way to save battery life and only record those stats when you want it to, but just about every other wearable lets you turn on SpO2 and leave it on. It’d be one thing if switching watch faces was easy, but it’s not. I run into syncing issues almost daily with the Fitbit Sense, so swapping watch faces isn’t my top priority most of the time. It’s inconvenient when it doesn’t need to be.
After the Fitbit Sense review period wrapped up, Fitbit told Android Authority that it plans to add SpO2 monitoring to the Fitbit app without users being required to use a specific watch face. This important change should roll out in the next few months. Fitbit has since rolled out more SpO2 clock faces to the Sense. The company plans to add SpO2 measurements to the Charge 3 and Charge 4 devices. Again, a specific timeline was not mentioned.
Sleep tracking continues to be a strong suit for the wearables company. As with other Fitbits, the Sense will track your light, deep, and REM sleep, and give you an overall score from 1-100 based on your heart rate, sleep stages, and time awake. Fitbit’s sleep score has always been quite accurate for me. Throughout the Fitbit Sense review period, I never noticed any major slip-ups with sleep tracking and it compared well against another favorite sleep tracker of mine, the ScanWatch.
Fitbit added snore and noise detection to the Fitbit Sense and Versa 3 in a September 2021 update. The Sense can detect and analyze the intensity of noises made during the sleep cycle using the built-in microphone. The info is available in the Sleep section and gives users yet another metric to gauge their sleep quality. Fitbit does recommend that the Sense’s battery is above 40% at night to ensure it functions correctly.
The Fitbit Sense has a new heart rate sensor. It’s using Fitbit’s new PurePulse 2.0 technology with an updated algorithm, which should provide more accurate numbers across the board. To test this, I went for a five-mile interval run with the Fitbit Sense, Fenix 6 Pro, and Wahoo Tickr X chest strap. See the screenshot below for the results.
The Fenix 6 Pro and Fitbit Sense both took a few minutes to start leveling out. After that, things remained pretty steady between all three devices. Notably, the Sense was a little slow to pick up on a few heart rate peaks in the first 20 minutes or so of the run. It also remained consistently higher than the Fenix 6 Pro and Tickr X by about 3-4bpm. You’ll also notice that it never got down to the same low 110bpm valley like the other devices did at the ~37-minute mark.
For general use, I think the Sense does just fine, comparatively. It was able to pick up on the stark changes in heart rate for the most part, even if it didn’t match down to the beat. This was a particularly high-intensity interval run, though. The Sense was most accurate between the 150-165 mark; anything higher than that and the Sense started to lose its footing.
The Sense will alert you if your heart rate is too high or too low during times of inactivity. My heart rate never triggered this feature based on the recommended heart rate threshold. If you feel like Fitbit’s estimates are off, you can set custom thresholds in the Fitbit app.
As per usual, I didn’t notice any issues with the Sense’s 24/7 heart rate readings. It’ll also display your target heart rate zones during activity just like the Charge 4. As I said in my Charge 4 review, receiving a buzz every time you change heart rate zones can be distracting. I turned these vibrations off right after my first run with the Sense.
Fitbit’s Active Zone Minutes are back, too. This is a useful and fun way to achieve the American Heart Association and World Health Organization’s recommended 150 minutes of activity per week. Read more on Active Zone Minutes in our Fitbit Charge 4 review.
Built-in GPS! Fitbit finally caved and added GPS to its whole smartwatch lineup, so no need to bring a phone with you on a run to get accurate pace and distance metrics.
The screenshot above shows part of my neighborhood run with the Sense (red) and Fenix 6 Pro (purple). These are the most accurate GPS recordings I’ve ever been able to get from a Fitbit. Coincidentally, this is one of the least accurate runs I’ve seen from the Fenix 6 Pro’s GPS.
In problem areas, like right before the bridge on Auburn St., the Sense was able to stick to nearly the exact route, while the Fenix 6 Pro showed me running into the road (I didn’t). Both devices were a tad wonky under the bridge. Then in the residential part of the run, the Sense followed my running path despite the heavy tree coverage. The Fenix 6 Pro, well, just look at the map…
I’ve run five times with the Fitbit Sense and each time it’s taken a few minutes to lock onto a GPS signal. This usually gets better the more you use a device. At least, I hope it will improve in this case.
Fitbit introduced heart rate zone heatmaps in the Fitbit app a few months ago. They’re wonderful. On Fitbits with GPS, you’ll get a heatmap of your outdoor route showing your heart rate zones. The Fitbit Sense also supports over 20 goal-based exercise modes and automatic activity recognition for the most popular sport profiles.
Menstrual cycle tracking is available on the Sense too, allowing you to track your period cycle, symptoms, and more. I was not able to test this feature out, though we have a detailed guide explaining how it works.
Smartwatch features: Promises shouldn’t sell products
Fitbit is still relatively new to the smartwatch game, so this is the part of the review where we usually critique the company the most. Fitbit has made progress in some areas, but it is still falling behind in many others.
The Fitbit Sense comes with Amazon Alexa support, just like the Versa 2 did. You can summon Alexa by long-pressing the side button. Notably, there’s no hot word support here. Alexa can handle simple requests like “What’s the weather?” and “Turn on my bedroom lights,” but more advanced commands aren’t supported. This isn’t the same Alexa you get on your smart speaker.
The voice assistant is still pretty slow to respond to simple requests, but I think it’s more an issue with voice recognition than anything else. Even responding to texts via voice dictation is slow compared to other smartwatch platforms.
While it wasn’t available at launch, the Fitbit Sense now has support for Google Assistant. It operates just like Alexa: long-press the side button, say your voice command, and wait a few seconds for the response.
Music support still comes standard on the Fitbit Sense. It has 4GB of total storage, but only ~2.5GB for music (or about 500 songs). You can download Pandora, Deezer, and local music files onto the Sense, but somehow Spotify support is still missing. This is something we’ve been begging for since the Fitbit Ionic days! Maybe the Fitbit Sense 2 or Versa 4 will have it. Who knows.
App selection in the Fitbit App Gallery is still far behind the Apple Watch, Wear OS, and even Samsung’s app store. And yes, navigating through the gallery is still as slow and painful as ever. Fitbit OS can still be quite laggy at times too. I asked if there were any processor or RAM upgrades, but the company declined to comment.
The Fitbit Sense gets most of the basic smartwatch stuff right, however. It gives you smartphone notifications, and you can respond to them via quick replies or voice dictation if you use Android. All Fitbit Sense models also come with Fitbit Pay support for contactless payments. I used it at a coffee shop and ran into zero issues.
Overall, it feels like Fitbit is treading water with Fitbit OS. There haven’t been any major tweaks in some time, and it doesn’t look like the app ecosystem is making much progress.
Fitbit Sense specs
|Fitbit Sense and Fitbit Versa 3|
|Display||1.58-inch touchscreen AMOLED|
336 x 336 resolution
Corning Gorilla Glass 3
|Battery||Smartwatch mode: 6+ days|
Charge time: (10-80%): ~40 minutes
|Memory||4GB (2.5GB available for music storage)|
7 days of motion data, daily totals for past 30 days
HR data at 1-second intervals during exercise, 5-second intervals all other times
|Materials||Sense: aluminum case, stainless steel ring for ECG|
Versa 3: aluminum case
Classic strap: flexible material similar to that used in many sports watches
|Sensors and components||Sense: Electrical sensors compatible with ECG & EDA app|
Sense: Skin temperature sensor
Versa 3: Device temperature sensor
Optical heart rate sensor
Built-in GPS + GLONASS
Ambient light sensor
Wi-Fi (802.11b/g/n 2.4GHz)
|Notifications||Call, text, calendar, email, music control, and much more|
40.48 x 40.48 x 12.35mm
40.48 x 40.48 x 12.35mm
Small strap: 140-180mm
Large strap: 180-221mm
|Colors||Sense: Carbon/Graphite stainless steel, Lunar White/Soft Gold stainless steel|
Versa 3: Black/Black aluminum, Pink Clay/Soft Gold aluminum, Midnight/Soft Gold aluminum
Fitbit Sense review: Price and competition
The Sense’s main competition is the new Apple Watch lineup. The Apple Watch Series 7 is about $100 more expensive and has an SpO2 monitor and a medically certified ECG sensor, while the Apple Watch SE undercuts the Sense by $20 and offers many of the same features.
Then, there’s the Fitbit Versa 3. It’s around $100 cheaper than the Sense, doesn’t have any of the more expensive (and underbaked) sensors, and is pretty much the same watch from hardware to software. I see no reason to buy the Fitbit Sense over the Versa 3 if you don’t need the extra sensors.
The Garmin Venu doesn’t have ECG or an EDA sensor, but it is one of our favorite multisport watches with GPS. Although you may find it priced cheaper than the Sense, its list price is actually slightly steeper.
Samsung’s Galaxy Watch 4 series is arguably a better buy for those looking for a better smartwatch option. It does keep tabs on some metrics that the Sense doesn’t, including body composition, but it does lack the accuracy of the Sense. The base model is also some $50 cheaper than the flagship Fitbit.
Finally, if you’re looking into buying the Fitbit Sense mainly for its health-focused nature, you should also consider checking out the Withings ScanWatch. It certainly can’t hold a candle to Fitbit’s smartwatch features, but the ScanWatch is medically certified for ECG and will soon be for sleep apnea detection too. It’s available for about the same price.
Fitbit Sense review: The verdict
The Fitbit Sense is all-around better than the Versa 2. I think you should consider upgrading if you would like a nicer watch with GPS. Should you buy it over the Versa 3? I don’t know if I can answer that in a succinct way.
Fitbit needed to prove that its EDA, ECG, and skin temperature sensors are worth the extra $100 over the Versa 3. The EDA sensor has the potential to provide useful insights into your stress levels, but it’s not there yet. The skin temperature sensor could be useful if you’re a little paranoid about contracting an illness or need some peace of mind. The ECG sensor in the Sense is legitimately useful, but likely not for a wide user base.
On its own, the Fitbit Sense is an impressive fitness tracker. It nailed the basics. GPS is here, it has a good heart rate sensor, and sleep tracking is as wonderful as always. But the Sense doesn’t exist in a vacuum.
For Fitbit to edge out the competition, it needs to deliver on all fronts: basic fitness and health tracking, hardware, and software. Fitbit’s hardware and fitness tracking efforts should not go unnoticed. But some of the other annoyances aren’t things we should be seeing on a (normally) $299 smartwatch, especially one that’s in its third generation. If Fitbit wants to compete in a world where the Apple Watch exists, it needs to be on its A-game. Right now, it feels like Fitbit is playing for the B-team.