Fitbit Flex

Fitbit has been playing in the activity tracker arena for a long time. It was back in 2008 that the company launched its original Fitbit device, but it was when the Fitbit One launched in 2012 that consumers really took notice.

The Fitbit One was stuffed full of great features, despite its small dimensions, but many still preferred the Nike+ FuelBand due to its wristband design. So, the Fitbit Flex was launched, providing the majority of the features found in the Fitbit One, but designed to be worn on the wrist.

What’s in the box?

Unlike the Nike+ FuelBand SE or Jawbone UP, the Fitbit Flex isn’t a sealed wristband unit. Although the Flex is worn on your wrist, the device itself is separate from the wristband. Making the most of this flexible design, Fitbit supplies both large and small wristbands in the box, and each band has an abundance of clasp points, to ensure a perfect fit for anyone.

Fitbit Flex

The wristband clasp is removable, so you can use the same clasp for either wristband. You can also buy spare wristbands, or collect a rainbow of colours to ensure that your Flex goes with whatever outfit you might be wearing. The Flex itself is quite tiny and slides into a cavity on the wristband. Since the wristband is made from rubber, it’s easy to slide the Flex in and out as necessary.

Like the Fitbit One before it, and the Jawbone up, the Flex uses a proprietary charging cable. You need to remove the Flex from the wristband, then place it in the docking cradle at one end of the cable, then plug the other into a USB port. Of course this means that if you run out of juice while you’re out and about, you won’t be able to charge your Flex as easily as you could a FuelBand, or even the Withings Pulse, which uses a standard micro-USB port.

Fitbit Flex Charging

Talking of charging, Fitbit claims that the Flex is good for five days of use on a full charge, which is probably a little conservative. I found that the flex lasted for close to a week before it needed to be plugged in and juiced up.

As well as the Flex and the two wristbands, you also get a USB wireless dongle in the box. You can plug this device into your main computer, and once you’ve downloaded the software, your flex will automatically synchronise its data whenever it’s close to your computer.

Fitbit Flex

The ability to wirelessly sync with your computer is great, and it allows you to check on your daily progress without having to get your smartphone out of your pocket. If you’re working at your computer with the dongle installed, you can just fire up the Fitbit website in a browser, and it will automatically display your latest stats. It is, however, slightly odd that you need to use the dongle even if your computer is Bluetooth 4.0 enabled.

On your marks…

With the two wristbands supplied, it really is easy to get a comfortable fit, while the extensive adjustability on each strap means you can decide how tight or loose you want the fit to be. Once the Flex is strapped on, you pretty much forget it’s there, and even if you’re training hard, you don’t end up with too much sweat trapped underneath it.

When you’ve attached the Flex to your wrist it logs every step you take throughout the day. From those steps it will also estimate the distance you’ve travelled and the amount of calories you’ve burned; just like pretty much every other activity tracker out there.

Fitbit Flex

I tested the Flex alongside the Nike+ FuelBand, and the two devices turned in near identical step totals each day. I later added a Jawbone UP to that equation, and all three devices were close enough to each other to assume that they all track pretty accurately.

Like the Jawbone UP and Fitbug Orb, the Flex will differentiate between you just milling about and when you’re up and about. The Flex will log very active minutes when you appear to be exerting a reasonable amount of energy. The Flex isn’t quite granular enough to ascertain when you’re actually running, like the Withings Pulse though.

The Flex will also track your sleeping patterns, but you need to remember to put it into sleep mode before climbing into bed. Simply tap the Flex quickly for a couple of seconds and it will switch into sleep mode, then do the same when you wake in the morning to switch it back.

Fitbit Flex

The Flex will monitor how long you’ve slept and how often you’ve woken during the night. It also breaks down your sleep time into deep and light sleep, giving you an indication of how much rest you really got.

Unlike the Fitbit One, the Flex has no built-in display. This means that whenever you want to check your progress you need to either login to the website, or get your phone out and check the app. The only indication of activity you get on the device itself are five, white LEDs – each one indicates 20 per cent of your daily goal. Tap the Flex twice and it will illuminate the as many LEDs as you’ve filled so far.

Fitbit Flex

This is where the Nike+ FuelBand SE really steals a march on the competition, with its multi-level LED display, all your data is just a button press away, without any need to fire up phones or browsers.

Also missing from the Flex’s repertoire is an altimeter. Whereas the Fitbit One will measure how many flights of stairs you’ve climbed in a day, the Flex provides no such information, which is a shame. That said, nether the Nike+ FuelBand SE or Jawbone UP have altimeter functionality either.

That syncing feeling

Before you can start to sync your data you’ll need to create a Fibit account, which is both easy and free. However, if you want the Premium features, you’ll need to pay a £39.99 annual subscription, which seems a little off considering you’ve just bought a Fitbit device – I think you should at least get a year’s subscription to the premium service thrown in. Thankfully, there’s more than enough functionality baked into the free version.

Fitbit Flex

The Fitbit web portal is beautifully designed and well laid out. Your dashboard is full of bright, colourful icons, and all the data is presented as widgets on a grid. This grid layout adds flexibility, with the option to move any and all your widgets around into a layout that suits you.

Even without customising the layout, it’s easy to see everything you need to know at a glance, whether it’s the number of steps you’ve taken, the amount of calories burned or the total number of very active minutes.

Fitbit Flex

You can set your own daily target, but the default of 10,000 steps is about right for an average day. Fitbit will, of course, award you with badges and trophies for being particularly active, whether that be hitting a very high daily step count, or reaching your daily target every day for a week. You can also see how your connected friends are doing, and your Fitbit dashboard will show you a league table of who has been the most active over the past week.

To make sure you can view and analyse your data anywhere and anytime, you’ll need to download the Fitbit app for your smartphone. The app is compatible with iOS devices from the iPhone 4S onwards, and a selection of Android handsets. The Flex uses Bluetooth 4.0 Smart technology, so your phone will have to support the latest standard – check out the Fitbit compatibility list to make sure your phone will run the app.

Fitbit Flex

The beauty of using Bluetooth 4.0 is that the Flex is always connected to your phone, so there’s no need to press any buttons to sync your device – as soon as you open the app on your phone it will display your latest stats.

Like the web portal, the app looks great and is incredibly easy to navigate. The app displays all your current and historical data, allowing you to compare how you’re doing today to yesterday, or the previous Sunday etc.

Fitbit Flex

You can also use the app to track your diet, which is pretty handy if your prime reason for investing in the Flex is to lose weight. The food tracking part of the app isn’t quite as good as in the Jawbone UP app, since Fitbit uses a US food database rather than a UK one and also doesn’t support barcode scanning. That said, I found most foods within the database, and there is the option to manually enter food too.

As with the Jawbone UP, you can use the app to set silent alarms on the Fitbit Flex. This is a great little feature, and it’s surprising how effectively the vibrating alarm wakes you up in the morning, without disturbing your partner.


While the Fitbit Flex is missing a few key features, much can be forgiven when you factor in the £79.99 asking price. That makes the Flex £20 cheaper than the Jawbone UP and a full £50 cheaper than the Nike+ FuelBand SE. But while the Flex is clearly a better option than the UP, thanks primarily to the UP’s lack of wireless connectivity, things aren’t quite so clear cut when it comes to the FuelBand SE.

The big advantage that the FuelBand SE brings to the table is its built-in display, which not only saves you the bother of having to get your phone out to check your progress, but also allows your activity tracker to be your wristwatch. Fitbit is clearly aware of this, though, and has already launched the Fitbit Force in the US, which incorporates a built-in display.

Fitbit Flex

If you’re looking to kick off the New Year with a healthier lifestyle and want a well-featured and affordable method of tracking your activity, the Fitbit Flex is a very tempting proposition. The device itself is comfortable and reasonably unobtrusive, depending on which colour you opt for. The bundle is generous, and the supporting app and web portal give you all the functionality you’re likely to need. The Flex isn’t waterproof, but then none of the competition is either – only the Polar Loop is waterproof, and that still isn’t available in the UK.

While I feel that the Nike+ FuelBand SE offers enough added functionality and app support to justify its price, many will find that the Fitbit Flex offers more than enough at a very reasonable asking price.

Update: As one of our readers has pointed out (that’s you Rick), the Fitbit Flex is waterproof and can be used while showering or even swimming. Strangely, Fitbit refrains from calling the device waterproof, rating it only as water resistant. However, Fitbit does state that the Flex can be submerged in water up to ten metres, essentially making it good for anything bar diving.

Score: 8/10


  • Multiple wrist straps bundled
  • Wireless dongle for your computer provided
  • Light and very comfortable to wear
  • Well designed app and web portal
  • Food tracking built into the app
  • Bluetooth 4.0 support
  • Good battery life
  • Tracks sleep
  • Tracks active steps
  • Share and compete with friends
  • Multiple strap colours available
  • Very reasonable price


  • No built-in display
  • No altimeter function
  • You can’t log exercise sessions
  • Food database is American
  • Not waterproof
  • Doesn’t display time of day
  • Proprietary charging cable
  • Premium Fitbit account costs £39.99 per year

Price: £79.99

Manufacturer: Fitbit