Fitbit Charge 2 v Fitbit Blaze: Which fitness tracker is best for you?

To say Fitbit was busy last year would be an understatement. It launched four fitness trackers, including the Fitbit Blaze and the Fitbit Charge 2.

When the Blaze was announced back in January 2016, it was the best that the company had to offer on the hardware, software and design front. But then the Charge 2 turned up later in the year and took things up a notch.

Read the full verdicts: Fitbit Charge 2 review | Fitbit Blaze review

Both devices have gone on to become two of Fitbit's most popular fitness trackers, which begs the question: Which one is the right Fitbit for you? We'll compare the two to help you find out.

Fitbit Charge 2 v Fitbit Blaze: Design

The most immediate difference between the Charge 2 and the Blaze lies in the design. Fitbit describes the Blaze as a "fitness watch", which essentially means it's taken its fitness tracker tech and put it into a slightly different – and arguably more masculine – form factor. The Blaze itself is pretty thin and sleek and is far thinner than the Apple Watch Series 2, for example. The module pops out and can be snapped into more strap and casing combos, with customisation a key factor. The standard band is rubber, but there are stainless steel and leather options available, as well as a new gunmetal casing.

The Charge 2 resembles the original Charge, and sticks to the trusted Fitbit band look and feel. Taking cues from its predecessor, it's actually much sleeker than the others. The larger black and white OLED screen is four times bigger than on the old Charge devices, though still not a patch on the Blaze's 1.25-inch 16 colour display, which looks pretty sleek.

Essential reading: Fitbit Blaze tips and tricks

While neither the Fitbit Charge 2 or Fitbit Blaze are winning any awards for design, which one you pick is very much down to preference. If you're looking for a fitness device to replace your watch then the Blaze is your best bet. Looking for something sleeker? Or to complement a wrist-worn item you already have? The Charge 2 works better. But what about features?

Fitbit Charge 2 v Fitbit Blaze: Features

In many ways the Fitbit Blaze and Fitbit Charge 2 are identical. Both track steps, calories burned, stairs climbed, active time, resting heart rate and quality of sleep. What's more, both boast several sports modes, which will track particular exercises using the built-in heart rate monitor.

Neither feature GPS built-in, but will connect to a smartphone to piggy-back the device's location data, which will be added to your runs. Both devices use SmartTrack, which automatically detects exercise and tracks it from within the app. That could be a brisk walk for the bus or a marathon – it all goes into your data stream.

Essential reading: Fitbit Charge 2 tips and tricks

Thanks to a fresh and much needed update to the Blaze earlier this year, any major differences in features between the two devices have been all but cleared up. For some time, the Charge was the stronger option due to its Cardio Fitness Level (Fitbit parlance for VO2 Max) and Guided Breathing offering. That's no longer the case.

The former allows you to wear either device when sleeping to ensure the tracker measures your resting heart rate. Then it takes your user profile – age, height, weight and fitness data – to give you a score. This score is your VO2 Max, which is a pretty decent indictor of how fit you are, and is normally only found on high-end Garmin sports watches. You can then make your score more precise by going on several runs of at least 10 minutes. We've carried out a big VO2 Max test to see how useful a metric it is on the Charge 2.

Then there's the breathing exercises. Using heart rate variability data, the Blaze and Charge guide your breathing by monitoring your heart rate to find a good rhythm. You can also complete a two-minute or five-minute session for a moment of relaxation, or use it to cool down after a workout.

And as well as the Blaze finally catching up to the Charge 2 with these features, it also offers FitStar – the smart workout company Fitbit bought last year. Three guided sessions have pride of place on the Blaze: warm up/down, 7 Minute Workout and 10 Minute Abs. It's hardly a game-changer, but it's an added feature for those who want to push themselves at home.

The Blaze and Charge 2 are also at parity when it comes to sleep features. Both of them do Sleep Stages, which uses your heart rate and a couple other sensors inside the bands to determine how long you spend in light, deep and REM sleep every night. Every morning, you can also check out your sleep insights via the companion app, which look at your sleeping habits and offer advice on how to improve them.

Fitbit Charge 2 v Fitbit Blaze: Heart rate

Both devices feature heart rate tracking and both use Fitbit's own PurePulse sensor. The performance is pretty similar on both devices: fairly accurate during moderate activity and steady running, which stayed within 5bpm of a chest strap during our testing. More intensive activities are a different story, though, with both devices suffering too much lag time to adequately track rapidly increasing bpm.

The Fitbit algorithm does a good job of sorting the laggy live data into useable after-workout reports – which is great. We don't have any problem recommending the Fitbit Blaze or Charge 2 for giving you feedback from a gym session. But the lag means that it's very difficult to use either device to make sure your ticker is hitting specific highs.

Fitbit Charge 2 v Fitbit Blaze: Notifications

Both devices feature smartwatch style notifications, which is the norm for any fitness band these days. But the Blaze's bigger screen allows for much better and richer notifications than the Charge 2. Both will display calls, texts and calendar alerts from your stock Android or iOS apps, but only the Blaze supports third parties.

You can read full messages on the Blaze, while the Charge 2 only offers snippets – in fact, it's only really prompting you to pull your phone out, not saving you the hassle of doing so.

Fitbit Charge 2 v Fitbit Blaze: Battery life

Fitbit promises five days of battery life from the Blaze, which was confirmed in our tests. Even with some tracked workouts, the Blaze expired after five days on charge. The Charge 2 battery will last about the same amount of time. They're both impressive in terms of longevity, although nowhere near as long-lasting as Garmin's Forerunners (running watches with fitness tracking smarts) or the Withings Steel HR.

Fitbit Charge 2 v Fitbit Blaze: Verdict

It used to be the case that the Charge 2 was clearly the more in-depth fitness tracker, with its ability to track VO2 Max and breathing alongside the rest of your health metrics. But since the update brought these features to the Blaze, this is pretty much evened things out in the features department.

However, the Charge is still a more discreet tracker than the Blaze, which will appeal to those who want to make a Fitbit their one and only wrist device. While neither device is perfect, this really comes down to how important you find notification support and which device you prefer the design of.