Fitbit Flex

Fitbit is already one of the biggest names in fitness gadgets, but the long-awaited Flex is the firm's first wristband. It follows a strong line of clip-on trackers including the Zip and clearly has its sights set on the likes of Nike's Fuelband and Jawbone's Up.

There's been a good six-month wait for the Flex since it was first shown at CES, so the important question is: was it worth it?

Looking at the specs on paper, there's a lot to like. It syncs wirelessly with smartphones, tablets, PCs and laptops, tracks your sleep and is waterproof.

Fitbit has also worked hard to make the Flex compatible with Android, although only the Galaxy S4, S III, Note II and Note 10.1 are currently supported.

The Flex has built-in NFC, which at the moment merely means you can launch the Fitbit app on your NFC-enabled device by rubbing the wristband on it.

Fitbit Flex review: design

The Flex tracker is separate from the rubber wristband, unlike both the Jawbone Up and Nike Fuelband. Although it's tiny, the band is 10mm thick at the display, so it's bulkier than you might imagine.

However, the strap is as thin as a normal watch, and as it's all flexible, it's comfortable to wear. You get two bands in the box: a larger one and smaller one. Optionally, there's an extra-large version available from Fitbit.

You get a choice of colours: slate or black. You'll be able to buy a pack with three extra bands: teal, tangerine and navy. We think the teal and slate bands are similar shades.

It's easy to pop the tracker in and out of a wristband: handy because you'll need to do so to recharge it every few days, and also whenever you get it wet. Fitbit says you can shower in it and, although that's true, the cavity in the wristband fills up with water and slowly seeps out.

It isn't easy to clean inside that cavity, and you'll more than likely want to spray some anti-bacterial cleaner in there regularly.

Like the Fitbit One, a proprietary USB cable is included for charging. Compared to the convenience of the Fuelband's built-in USB connector, the Flex is awkward.

Fitbit Flex review: battery life

In my tests, I found the battery lasted slightly longer than the claimed five days, but that was with minimal real-time synching: a new feature introduced in the iPhone and iPad app. Thanks to the use of Bluetooth 4.0, the Flex (just like the One) can now give you real-time updates via the app for the number of steps you've taken.

In fact, Nike's app has been able to do this from the start for NikeFuel, but at the expense of battery life.

One complaint we have here is that the Flex didn't last long after we saw the initial 'low battery' warning via the web dashboard, and stopped working without further warnings on the device itself. The One and Nike Fuelband both lasted at least 48 hours after the first warning, giving you plenty of time to get around to charging them.

Fitbit Flex review: display

One of the biggest advantages of the Nike Fuelband is its display, which shows the time, fuel earned, steps and calories. The Flex merely has five LEDs which work in a similar way to the Fuelband's progress meter.

Flex tracker

Each LED represents 20 percent of your daily goal, so you can see roughly how you're doing. It will give a celebratory flash and the band will vibrate when you hit that goal, but that's all.

Fitbit says you don't really need a display when you have real-time stats on your iPhone, but we'd tend to disagree. The fact the Fuelband can show useful data without a phone means you don't need to take your phone on a run (or even get it out) to see the time or how much fuel you've earned.

Fitbit Flex review: stats and accuracy

A wristband will never be as accurate as a clip-on tracker, and that's another slight disadvantage of the flex. For the entire time I tested the Flex, I also wore a Fuelband and clipped on a Fitbit One for comparison.

On an average working day in the office, the Flex reckoned I'd covered 3.5 miles and taken 8,281 steps. The One said it was 3.2 miles and 7,185 steps.

Looking at the data from the Fuelband, it was the most conservative with 3 miles exactly and 6,116 steps.

On a much more active day, the Flex reported I'd walked 7 miles exactly and taken 15,951 steps. The Fuelband clocked it at a mere 4.4 miles and 9.084 steps, so the Flex, even if it's a bit generous, certainly made me feel better.

The Fitbit One again sat in the middle with 5.94 miles and 13,739 steps. Taking the relatively safe assumption that the One is the most accurate (previous tests have shown it is), the Flex overestimates steps (and distance) by around 10-15 percent.

Flex Fitbit dashboard web

Fitbit Flex review: website and app

Fitbit has just launched a brand new dashboard for its website, and it's a big improvement over the old one. Gone are the fiddly, too-detailed graphs and in their place are big, easy to read tiles which can be rearranged to your liking.

Hover over a tile and it will show the percentage towards your daily goal, and if you're looking at the current day, you can click to see a bar chart for the last couple of weeks and there's a link to extra information such as food and activity logging, plus others.

A new addition is the Very Active Mins graph. This is a handy metric for those who don't want to compete on steps or distance with friends. If you don't have the time to walk 6 miles per day, this offers a more achievable goal - as long as you're willing to put in the work.

The default goal of 30 'very active' minutes is harder to hit than you might think, so it's a good motivator to do some proper exercise every day. The government currently recommends a minimum of 150 minutes of moderate-intense aerobic exercise per week, so if you hit this goal every day, you'll do an extra hour above the minimum.

Fitbit app sync Flex

The 'Sleep' tile shows how long you actually slept and hovering over it reveals how many times you woke up in the night.

Using the bundled Bluetooth dongle, the Flex will sync whenever you're within about 10ft of your computer and the website will also flash up a warning when your Flex battery is low.

An app update should be on the way, but for now, the iOS and Android app is functional but not nearly as pretty as Nike's iPhone app.

Fitbit Flex review: bottom line

The Fitbit flex is a mixed bag. On the one hand it's more convenient than the Zip, Ultra or One since you can wear it all the time. With clip-on trackers, you'll find you regularly forget to swap them over when you change clothes, and the One is fiddly to use for sleep tracking.

The Flex does almost everything the One does (including waking you up with its vibrating alarm), but doesn't track floors climbed and lacks a proper display.

Given both cost the same, the choice between them is tricky. It's really down to your personal preference: do you want a discreet clip-on tracker, or are you happy to wear something on your wrist all the time for tracking both activity and sleep?  

Although the Nike Fuelband costs £50 more and does even less than the Flex, it's still a worthy opponent. It's a great motivator and doubles as a watch.

I wanted to like the Flex more, but it feels too much like a first-generation product. It's the right price, but compared to the Fitbit One and Nike Fuelband, the lack of a proper display is a bit disappointing.

If tracking sleep is one of your top priorities, the Flex is a decent choice, but otherwise, the One is better.

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