Fitbit Flex 2 review

Updated: Living with Fitbit's first ever swim tracking wearable

Fitbit Flex 2 is the first swim-friendly fitness tracker from the company and we can almost hear the collective sigh of relief that we can finally have the waterproof tracker we've been waiting for.

In the face of the Misfit Speedo Shine 2 and gamut of other water-resistant trackers, it's taken Fitbit a long time to answer the call of swimmers. And on paper at least, the Flex 2 looks like the real deal.

Wareable verdict: Fitbit Charge 2 review

Priced reasonably at £79.99, the features aren't as advanced as the Fitbit Charge 2, instead it's geared towards the entry level crowd who want a tracker that's slim, versatile and of course, waterproof.

Aside from the simplicity of form factor and usage, the Flex 2 is a far cry from the likes of its years old predecessor, and that's a very good thing. We gave our initial verdict after a few weeks of testing and now that we've spent more time with the device on our wrists, here's what it's like to live long term with it.

Fitbit Flex 2: Design and comfortFitbit Flex 2 review

Flex 2 really is a slim little tracker that's hardly noticeable at all on the wrist, which is a nice change of pace. The wearable is much slimmer in appearance than the first Flex because the tracking module is 30% smaller. The Alta looks like a beast next to it. Okay, not really, but Flex 2 is noticeably more petite and is without a display. It's also the ideal piece of fitness tracking camouflage, especially when the module is tucked away behind a bangle or pendant.

Our feelings haven't really changed on this front having spent more time with it around our wrist. It's still not much of a looker, but it's as light and comfortable tracker you can wear day and night.

Read next: Fitbit smartwatch investigation

In a Classic band, the textured elastomer is soft but not so pliable that you'll be able to clasp it easily. One of the biggest criticisms of previous Fitbits including the Flex has been the suitability of the clasp mechanism. You were just never fully satisfied that it would stay put. It's an entirely different prospect with the Flex 2. Once the clasp is in place, good luck trying to yank it back out again. That does make it a tad more fiddly to get it off your wrist in a hurry, but we're all for the added secureness you get with the Flex 2.

If you want to change up your Flex 2, there are plenty of options. Unlike the old device, the new Flex is chasing the fashion conscious by letting wearers switch out the original bands for bangles, pendants and a whopping selection of seven Classic bands.

Fitbit Flex 2 review

The colours you can choose from in the Classic collection are: black, navy, magenta, lavender, pink, grey and yellow. There are also £29.99 three-packs you can get with an assortment of colours, called the Sport Pack (navy, grey, yellow) or Pink Pack (magenta, lavender, pink). Alone, a Classic band isn't too expensive at $14.95.

The fancier options include Luxe bangles in silver (£69.99), gold and rose gold (£79.99). Then there are the pretty little pendants that come in silver (£69.99) and gold (£79.99), with a one size 17-inch chain.

Fitbit Flex 2: Notifications

Fitbit Flex 2 review

The device is similar to other screen-free fitness trackers where there are LED lights to notify you about calls, texts and also hourly reminders to move. Lifting your arm up will make the vibrations stop but the lights will keep flashing for phone calls.

At the moment, it doesn't seem like the lights can be personalised to your liking. Rather, Fitbit has a default pattern of lights and vibrations to help you differentiate between calls, texts, silent alarms, reminders to move and daily goal progress. No third-party notifications are recognised either, which is frustrating.

Essential reading: The big swimming tracker group test

One of the things we just haven't got to grips with is the notification LED system and how that corresponds to different notifications on your phone. It will remind you of the discreet notification support Misfit uses on its Shine and Flash fitness trackers.

It's fine as far as viewing tracking progress throughout the day. The more white lights that illuminate on the band, the closer you are to your target. It's not quite straightforward when you feel a vibrating buzz at the wrist and see a colour flash up to signal that someone is trying to get in touch. Bottom line, you're still going to be looking for your phone to deal with the notification.

Fitbit's explained that the team wanted to keep it simple for now but isn't closed off to the idea of customization. Right now, tapping on the Flex 2 shows your goal with a green light on top and white lights showing progression, the yellow light means alerts and blue stands in for both phone calls and texts. The latter is differentiated by a longer vibration for calls.

We're hoping Fitbit will eventually allow customisation to make it more personalized. Thankfully the vibrations themselves aren't too jolting.

Fitbit Flex 2: Tracking

Fitbit Flex 2 review

The Flex 2 is as simple as you can get. It's capable of tracking steps, calories burned, active minutes, hourly activity and sleep, all of which can be auto-detected with the SmartTrack feature. Currently, the exercises that can be auto-tracked include walking, running, outdoor bike rides on pavement, elliptical, aerobic workouts (Zumba or cardio kickboxing) and sports like tennis, basketball and soccer (among others according to the app). We used the Fitbit Charge 2, Samsung Gear Fit2 and Apple Watch Series 2 to measure the step counting and all matched up with the Flex 2 without any major issues.

You'll have to head to the app to see how many steps you've taken and to check on specific numbers for goals, but tapping on the front of the Flex 2 will elicit corresponding lights. Each white light represents 25% of your goal, meaning if your goal is 10,000 steps and you see four white lights, you've completed at least 7,500 steps. When you reach your goal, the Flex 2 vibrates and the lights flash in 'celebration'. Tapping again to check your progress will continue to show the same row of flashing lights.

Sleep tracking has been pretty good and I've used it against the Charge 2 ‚Äď which has been pretty accurate ‚Äď and the FitSleep device. On the whole, Flex 2 has matched up well with the Charge 2 and only a few wake-up times have been off. It also synced up with how much time I spent sleeping.

Fitbit Flex 2 review

Running with Flex 2 and TomTom Spark 3 GPS running watch

Aside from swim tracking (which we'll get onto next), we put the automatic run tracking through its paces as well. You won't get any advanced metrics like you'll get on a GPS running watch, instead opting to record exercise duration, calories burned as well as measuring the impact it has on your day and active minutes.

As you'll see from the screenshots below, it's a case of the Flex 2 being in the ballpark as opposed to being on the money. The workout duration is a few minutes off and calorie is roughly the same as the TomTom Spark 3 running watch we tested it against. Unlike the Charge 2, there's no heart rate monitor or ConnectedGPS, which means you won't get running distances even if you take your phone along for the ride.

Fitbit Flex 2: Swimming

Fitbit Flex 2 review

One thing the Flex 2 really does have in its favour is its swim tracking capabilities. It can be worn up to 50m (including in saltwater). Swimming can be auto-tracked with duration and laps of four strokes monitored: freestyle, breaststroke, backstroke and butterfly. For non-swimmers, you won't have to worry about hopping in the shower with it on or heading out to the beach.

If you plan on swimming with the Flex 2, know that it won't give you the most advanced metrics. What you do get is an overview of your calories burned in a chart, the amount of time you've swam, distance, pace and impact on your day.

Specific strokes aren't noted in your app, and Moov Now remains one of the few swim trackers capable of this. You'll also have to turn on the swim track feature before you hop in the pool. It's turned off by default to conserve battery life "for those who do not regularly swim, so make sure you venture into the app to sort. We explain all in our Fitbit Flex 2 tips and tricks.

Fitbit Flex 2 review

You must also swim continuously for SmartTrack to work. Meaning if you're not a strong swimmer, the Flex 2 has a harder time recognising your strokes and you'll need to adjust active running minutes (the amount of time it takes to recognise you're swimming) in the Fitbit app. You can also set the pool size to increase tracking accuracy as it seems to be set to 25 metre pools as a default.

Read this: Swimming with Apple Watch Series 2 and Fitbit Flex 2

As long as you're willing to accept that you're not going to get myriad of swim metrics here, it's still a pretty solid swim tracker. At the most it's been three or four lengths of matching the swimming watches we've tried it against. The baseline data is going to be enough for casual swimmers throwing in a few swimming sessions as part of their weekly routine.

One thing to remember is the inclusion of swim tracking is huge in itself. It doesn't have the other features stocked in higher-end fitness trackers like the Garmin Vivoactive or TomTom Spark, but the Flex 2 is definitely the cheapest of the bunch and you're still getting a good experience here.

Fitbit Flex 2: App

Fitbit Flex 2 review

If you've used a Fitbit before, you'll know what the Flex 2 app looks like since it's the exact same interface.

It's a good ecosystem, full of social challenges with badges to earn, all clearly laid out and easy to use. The release of Flex 2 and Charge 2 came with a set of new challenges as well that are now available across the Fitbit lineup. Called Adventures, you can choose from various step goals that take you through different locations. For example, it takes 15,000 steps to 'walk' on the Yosemite Vernal Falls hike. That means every step you're taking at home, work, wherever is then matched up to the hike Fitbit's set up in the app. You even get to see your steps mapped out with the app telling you how many more steps you need to go.

You don't have to complete the whole thing immediately, though the app gives you a daily destination with points to meet based on your seven day step average. Along the way, smaller step goals unlock little things to keep you motivated.

Aside from that, you get your usual gamut of food, water and weight logging. Days are presented on the main screen, and you tap a metric to get a broader look at your performance. For example, tap on the sleep score for the day and you can take a look at your sleep over time, and filter by day, week or month.

Overall, Fitbit's app is one of its strong points. Easy to use and clear, it offers enough data without feeling overwhelming. You can also sync up multiple devices to one phone. In the past it didn't always work right, and you'd have to un-sync, re-sync and go through a whole process but now it works like a dream.

Fitbit Flex 2
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Fitbit Flex 2: Battery

The five-day battery life of the Flex 2 is surprisingly mediocre. Of course, it's a matter of how you use the tracker, but I'd expect at least seven or more days since it doesn't rely on a screen for notifications.

For the first test run, we used it with call, text and notifications to move turned on, meaning it buzzed whenever these things happened. It was on to track activity as well. Interestingly, the Flex 2 stayed true to the paper description (unlike the Alta) and lasted five days.

If you turn off notifications and only used it for activity tracking you can get up to nine days. It's clear that with notification support, activity tracking and swim tracking all switched on, it does mean the battery takes a hit.

Charging it is a similar process to the Fitbit Blaze: you have to remove the tracker module and insert it into the USB charger. Just be sure to pay attention how the Flex 2 clips in place into the cradle. We've managed to place it in incorrectly on a few occasions and been left with an uncharged device.

We prefer the clasp style of Alta and Charge 2 for convenience, but it's not a deal breaker by any means. For such a small device that doesn't do that much, charge time took about two hours.

Fitbit Flex 2
By Fitbit
Has living longer with the Flex 2 altered our opinion of the waterproof tracker? Yes and no. We still feel the same about the design and the confusing LED light-based approach to notification support. Battery life still doesn't blow us away either, but it will get you a week of tracking. We are more positive about its core feature and that's the swim tracking. Yes, it is basic, but it serves up a better swimming experience than similarly priced trackers. Fitbit’s software still lack those meaningful insights we crave for, but does the basic activity tracking well. The SmartTrack tech is a bonus, but again delivers very basic information. If you like swimming and can live without the more advanced metrics of a dedicated swimming watch, then it’s still a decent buy.

  • Waterproof in fresh and saltwater
  • Solid swim tracking
  • Comfortable to wear
  • Good value for money
  • Confusing notification support
  • Swim metrics are basic
  • No third party notification support
  • Basic design still a little drab

What do you think?

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  • JDonk·

    Avoid fitbit! I bought a fitbit charge for my wife at dick smith. The first one did not work straight out of the box, would not charge at all. Dick smith replaced immediately, same day as purchase. A few months later the new one stopped charging. Again, Dick Smith replaced with a brand new item. Now, 9 months later, this 3rd fitbit charge will not charge, the battery will not charge.

    Subsequently, Dick Smith has closed down in my area so I can not return for a refund.

    I contacted Fitbit, who are saying the original purchase is out of warranty but they will replace with the same model, but will not refund. They don't have enough faith in their own product to give a warranty on the brand new replacement fitbit charge thats only 9 months old!! I asked if the replacement they are willing to send will have a warranty but they didi not reply.

    They also will not allow me to pay the difference to upgrade to a better model!!

    Well, if you ask me thats pretty poor, they should write a book on how to lose customers because thats what they've done in this situation. Not only me but everyone I know I tell how bad the product is and the lack of faith they have in their product. I strongly recommend buying a more reputable brand.

    Fitbit is a waste of money and you will more than likely be disappointed.

    • Mical·

      I have two Fitbits and haven't experienced any problems.  I've also not been disappointed with them.  In other words, they are not a waste of money.

  • scarletanne·

    Do the bands from the fitbit flex also fit the new fitbit flex 2?? 

    • l.prasuethsut·

      No, the new Flex is a completely different design.

  • Sunniebeme·

    Does Fitbit Flex 2 track water aerobics activity?  I do many 45 minute classes each week and I now manually add the activity & what I think the calorie burn is, but I would really love to know what it really is. 


    • Blue6225·

      Did you ever get the answer to your question about Fitbit Flex 2 tracking water aerobics activities???

  • Scanny76·

    Bought 2 flex 2's, both cannot compete the set up phase. Tried on my iPhone and pc, no success! This is a massive product flaw and there are so many people in the same boat. Fitbit are now offering a full refund....very disappointed but glad I found out it's a dud now rather than struggling with warranty claims later. Never again Fitbit.

  • cblue·

    not real thrilled with my new flex2.  Does not really track biking at all and I am lucky to make 3 days on the battery charge.  I am going to try to return it to Best Buy.

    • Jo2Dajo·

      to get your bike track in, you'll have to place the bit on your shoe. Since riding a bike doesn't require your arms moving it won't track

  • Mbrk·

    A change is needed re: charger. Too often, I place the Fitbit2 in the charging jacket, only to find that I placed it in backwards and it didn't charge overnight. FB2 and charger design should be updated so that FB2 only fits in the correct way

  • Bubalouis·

    I was really pleased when I changed from the Charge to Flex 2. I bought the bangle and found it much more confortable, so much so that I didn't notice that it had disappeared from my wrist during a dog walk today!!!! Very expensive mistake, the bangle is obviously not very secure. Just wondering if anyone else has been as unfortunate.

    • Loritr·

      Does the Fitbit Flex 2 track the difference between regular steps and going up stairs?

  • pisces0304·

    I bought a Flex 2 October 13. The Flex 2 seemed to work fine for the first 30 days. Then I noticed the battery was running down very fast. I switch back and forth between my HR Charge. One day I noticed my water workouts were not listed on the Log page for 4 days. It seemed to only track when I had the Charge on. I restarted the Flex 2. It seemed to work for a few days tracking on the Log page. I then removed it from my phone and tried to "Pare" it thinking that might do something. Could not "Pare" it. Texted with Fitbit for 3 hours and did everything they said and it still did not "Pare". I ended up taking it back for a refund. And yes, I did the Apple update on my phone and did the Fitbit App update. I am really disappointed in Fitbit. I had always been able to use my original Flex in the pool for swimming, water aerobics and finning, so I just recharged it and put it back on. It tracks great in the water. Good luck everybody.

  • EricaJ·

    I am confused ... does my brand new Fitbit Flex2 track my heart rate?????

    Also, why would anyone tout a product that counts steps when it's counting how many times your arm moves??????

    • j.stables·

      No heart rate on Fitbit Flex 2.

  • Carefuldaughter·

    I like my Fitbit Flex 2 Tracker and the bangle bracelet that I bought for it.  I've only had it a month or two so far.  The only complaint I would have at this point is how often I have to charge it.  When reading reviews before I purchased it, people were saying that they only had to charge it every five or six days, where I find I have to charge mine at least every three days.  That could be because of my activity level, though, as I normally work 2 jobs M-F for a total of 13-14 1/2 hours a day, all of it standing.  It just didn't dawn on me when purchasing it that I would need to charge mine so much more often than the reviews I was reading.

  • Carefuldaughter·

    I haven't had my Flex 2 Tracker very long but I do like it.To date my only disappointment would be in how often I have to charge it. I was thinking I'd only have to charge it every five or six days like the reviews I was reading, but I have to charge mine at least every two or three days.  I'm very active M-F, working 13-141/2 hours every day, all of it on my feet, so I'm hoping it's because of that. It just didn't occur to me when I purchased it that I'd need to charge it so much more often than others do.

  • Asquared·

    The Flex 2 is the first tracker I've had and so far, I'm happy with it.  I do agree with a previous comment about having to charge is fairly frequently. I think I am only getting 3 days between charges, maybe 4 occasionally, certainly not 5.  Somewhat inconvenient but not a deal breaker for me.  

  • Gee·

    Bought one for me and one for my wife.  Couldn't get my wife's to synch, called their tech support and wasted my time dealing with non English speaking people. Returned it and got my money back.

    Mine worked for 2 weeks and now will no longer accept a charge.  Tech support tells me I put it in the charger incorrectly.  Not!  Pretty clear to me that one way is correct and the other way, the contacts won't align.  I'm a tech person so I'm 100% positive that's not the problem.  It goes back tomorrow, I'll be getting my money back and I'll try something other than fitbit.  

    I understand having issues but how a company deals with problems is the true test. Fitbit fails there too.

  • Steverad·

    Radman says

    I have had 3 Fitbit flex trackers. On everyone the band tears after about 6 months. Save your money.

  • SarahB72·

    I've had the Flex 2 for two weeks. It was brilliant the first week and logged all my swimming properly. However this week it told me I'd done a 10 min swim when in fact I was blow drying my hair! It's done that twice. And it didn't log my actual swim on Wednesday so that was disappointing. It also missed a couple of walks although I was texting whilst walking so maybe it's because my arm wasn't moving much. I'm considering sending it back but are there any better products for swimming out there?

  • pips·

    does the Fitbit Flex 2 show the time??

  • Martin3·

    i purchased a fitbit flex 12 months ago. It came with a 12 month warranty. Ive had the device replaced THREE TIMES. They are not built to last. Martin

  • Cinda·

    I received the Flex  2 fit bit as a gift. The battery goes dead in 2 days. I wish I would of never received it. It is NOT WORTH THE MONEY, SO DO NOT BUY THIS FLEX 2 FIT BIT 


  • shutthaduckup·

    My FitBit One was the BOMB! But then, I washed it....again :-(  THIS time, I could not revive the poor thing.

    After some research, the FibBit Flex 2 "seemed" like the one for me because I get most of my exercise in the pool. However, I am waiting for someone to answer whether or not the Flex 2 tracks TREADING or WATER AEROBICS? Anyone know? Anyone?

    I hear complaints about the Flex 2 requiring frequent charging; and it does not monitor heart rate; and does not monitor climbing steps. What else?

    And if NOT the Flex 2 - what else is on the market? I DO NOT want anything that connects to my phone - I don't mind the app being seperate.

  • MaryKelly·

    This past year, I received a Fitbit Flex 2 as a Christmas gift.  It worked well for several months.  In fact, it helped me lose 17 pounds through monitoring my calories and activity.   Yeah! 

    But the real reason I wanted to use Fitbit was for my insomnia.  It confirmed that I experience chronic, disruptive, restless, awake sleep patterns every night.  

    THEN all of a sudden I lost the charting which broke down the nightly interactions.  I followed some of the cues I found online for this exact same problem -- to no avail.  Removing Fitbit and Reinstalling Fitbit does not correct the problem.  

    What is the FIX?

  • Chicago·

    I purchased a Flex 2 in January 2017  from Fitbit for 50% off after several issues with an original Fitbit. It is now the middle of May and I have had 3 replacements for the original Flex 2 tracker. ( I have probably been without a device for a month of that time.) The battery life is considerably better but after just a couple of weeks it totally stops charging.This time the notification function quit, and after  multiple troubleshooting attempts, it just died. I have been given the option of another replacement or 50% off another device. I appreciate the company's willingness to provide replacements, but why can't they develop a better product. Obviously I would not recommend this item.

  • marshmiranda·

    I purchased the fitbit flex 2 in USA a few days back as i am a swimmer. I use it with a Windows Lumnia 640 xl installed with the windows 10 OS. The flex  will not work on the Windows OS 8.

    It does recognize swimming activity and the time i swam very well. I am currently doing more tests and will make my decision on the data accuracy after a week. 

    In terms of statistics of my swim data, the software lacks the ability to help you compare your swim workouts in a single screen. I need to keep switching between screens and understand how i performed 10, 15, 20 mins in my swim which is too much effort and confusing at times. I wish they could let me export only the swim data for a week/month/year. Currently they just dump you with all the data (Swim, Steps, Walks, Running etc) available via their download data link. The data file does not let me sort swims once downloaded and hence i do not get any valuable data to make any sense of my progress.

    It would be also great if they would notify me about my activity progress via the vibration function. e.g. I have set the minimum time for recognizing the swim activity to 10 minutes. when 10 mins are up it should vibrate and notify me rather than make me stop in the pool and look at the clock, which breaks up the exercise sync.Also user configured notifications for preset times i.e. 10, 20, 30 mins would be an added advantage as the same will let me know how long i have been swimming a stroke and will let me change my stroke if needed. currently they advice me to use the alarm function which is useless because my swim schedule varies on the weekend. I would not want the flex 2 to keep vibrating at 6am on a sunday morning every 10 minutes while I am sleeping. If i take it off my hand at that time i will not be able to track my sleep.

    As far as the step count is concerned, I have doubts in the data accuracy. They say i walked 30000 steps, however all i did was sat in my office chair and then walked 100 meters to my motorbike and rode back home.  I think it detects the vibration in my motorbike.

    Notifications of calls texts etc. do not work on the windows phone. All i can do is set an alarm for different times in a day and it will notify me. That helps to some extent.

    Overall in terms of look and feel this product is good and may serve the purpose of people who are into step tracking only. If you look for making sense of the data you collected via swimming, this is very very limited. They only provide you data of steps, distance and calories which is useless for swimmers. we want to know a single screen comparison of how long we took  to complete a stroke, what is the intensity and are we doing better or are we just doing what we did yesterday. 

    Seems like fitbit made this product for swims but kept out the main part making sense of the data collected via their software.