Fitbit Blaze review

Fitbit's closest thing to a smartwatch is decent, but no gamechanger
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Fitbit Blaze
By Fitbit
For people starting out with fitness, the Fitbit Blaze is a decent all-rounder and the best tracker the company has produced to date. The Blaze offers a spectrum of stats for most pursuits, including Sleep Stages and Cardio Fitness Level based on VO2 Max, but not all of them are perfect in nature. Having to take a phone to benefit from GPS accuracy, wayward HR stats at peak exercise and undercooked FitStar workouts ensure the Blaze pales in comparison to specialist fitness wearables – and buyers would do well to peek at the forthcoming Garmin Vivoactive HR first – but its size, diversity, user friendly stats and strong app make it easy to recommend for beginners.

  • Great all round stats
  • Top beginner friendly app
  • Bags of battery life
  • Guided workouts basic
  • HR tracker not the best
  • No GPS without smartphone

(We first reviewed the Fitbit Blaze way back in March 2016, but since then Fitbit has been updating its smartwatch-fitness tracker hybrid. We've come back to update our review.)

Now a household name in the world of fitness trackers, Fitbit has started to find its place in the world. While it's launched the Fitbit Ionic, its first real smartwatch, the Fitbit Blaze is a case of the company dipping its toe in the water.

The "fitness watch" offers familiar tracking with more advanced fitness features and a Fitbit heart rate monitor, which the company hopes will appeal to the armies of weekend runners and gym goers that head out to the local park early on Sunday mornings.

Essential reading: Fitbit Charge 2 review | Fitbit Flex 2 review

The Blaze's marketing portrays it as the fitness fan's new best friend – a tracker for the gym that's also at home in the boardroom – but is it the right fitness device for you? Read on to find out.

Fitbit Blaze: Design

Fitbit Blaze review

It's clear that Fitbit was keen to move away from the dorky black plastic bands that have dominated its design to date. Customization is now the buzzword, and that's a crucial element of the Blaze, but something the company is also focusing on across most of its range.

The tracker itself is a black plastic square that snaps into a stainless steel frame, which has a removable strap. The idea is that you can buy new couture straps and hot swap the unit between 'workout friendly' and 'evening drinks ready' looks.

Essential reading: Fitbit Alta HR review

The ensemble is an improvement over the Surge (Fitbit's existing sports watch and the Blaze's nearest cousin) although not quite as nice up close as the press pictures suggest. The gap between the frame and the unit is more pronounced, and the device itself seems to be all bezel and no screen.

Fitbit Blaze review

While those are the negative first impressions, the wafer-thinness of the watch itself is the biggest positive. It's impossibly slight against your wrist, no larger than a normal watch in truth and brilliantly light, which makes it comfortable to wear all day.

The panel itself is a tidy 1.25-inch 16 colour display, and if you up the brightness it looks pretty slick. It's touchscreen as well, so you can swipe through the options on screen. The left button is a back key, while the two to the right are used for selecting options mid workout when your fingers get sweaty.

Fitbit Blaze review

It's not an always-on display, which means the screen goes black when not in use for power saving reasons, and we have to say it's not the most responsive when you want to flick your wrist to see the time.

On the Blaze itself there are only options for Today (today's stats), Exercise (run, bike, elliptical, other), FitStar (set workout plans), Relax (guided breathing), Timer (stopwatch and countdown), Alarms and Settings. It's pretty simple, but weirdly when you go into an option, it stays on that menu when you return to your normal day – meaning that when you flick to see the time, you're presented with your stats, not the watch face. In short, the slight nuances of the watch could be better thought out. Oh, and there's no waterproofing, with only basic water resistance means that you're best off removing before showering. Swimming is a big no-no.

Fitbit Blaze: Features

Fitbit Blaze review

So what does the Blaze do? Well, effectively it's the Charge HR with an OLED screen, guided workouts and more smart notifications.

It tracks steps, calories burned, stairs climbed, active time, resting heart rate, and both sleep stages and quality of sleep. What's more, it has several sports modes, which will track particular exercises using the built-in heart rate monitor, and act as a running watch so long as you take your smartphone along to lend its GPS – more on that shortly.

FitStar – the smart workout company Fitbit bought in 2015 – also has pride of place on the Blaze, with three guided sessions that appear on the watch: warm up/down, 7 Minute Workout and 10 Minute Abs.

Essential reading: Fitbit Blaze v Apple Watch Series 2

It's a pretty complete set of fitness metrics that will please anyone shopping for a top-end activity tracker, though the lack of GPS is the only real blemish on the spec sheet. You can use Fitbit's ConnectedGPS feature if you're willing to strap on your smartphone when it's time for a run, but built-in GPS has become more commonplace in fitness wearables since the Blaze first launched, and its absence is felt even more a year on.

The only other real omission is a smart alarm – one that's designed to wake you up in the lightest part of your sleep cycle. It's a popular feature on other trackers, but hasn't made it to the Blaze, which is strange given the device's new Sleep Stages feature. There is a silent alarm, which uses vibrations to wake you rather than a horrible bleeping.

Fitbit Blaze review

And then there's Relax guided breathing, a feature carried over from the Fitbit Charge 2. There are two modes: two-minute breathing and five-minute breathing. Each one tries to gauge your breathing and tailors guided breathing to your breath. You inhale, you exhale, you stare at the Blaze's tiny screen to match the animation and make the background sparkle. It works as advertised, but it also lacks the nuanced vibrations that would allow for truly concentrated breathing, making the whole thing feel a little tacked on.

It's a decent set of features – but do they work? For some of them, we had to get sweaty to find out.

Fitbit Blaze: Activity tracking and accuracy

Fitbit Blaze review

There's so much going on with the Blaze, we need to break down the features to study the accuracy.

First up, steps and sleep. We've put the Fitbit Blaze up against other step trackers, but as ever, the problem is that they all use different algorithms. With the Blaze, it's the same deal as we've found across other Fitbit devices like the Alta HR - there's a tendency to be too generous. But it's not a massive difference, and trying it against the likes of the Misfit Shine 2 we found it to be very close, just a bit over. Wrist-based step tracking is never going to be spot on, but we have no major qualms in this department.

Sleep tracking has also proven pretty accurate, and toilet breaks were uniformly registered on the nightly results, which is always reassuring - when you know you've got out of bed and it doesn't show on your sleep tracking, it's a cause for concern. Since our initial review, the Blaze has gained Sleep Stages, which uses accelerometer data, heart rate variability and algorithms to track when you're in light, deep or REM sleep. From our vantage point, sleep stages seemed to work well, though the data is useless without the companion app's Sleep Insights feature, which is slowly making its way across Blaze devices as we write this.

Sleep Insights are Fitbit's way of serving up, well, insights - but actionable ones. Fitbit will get to know your sleep and activity habits better over time, and start offering you advice, like suggesting you don't miss your regular evening jog because it noticed that when you do, you don't usually sleep so well.

Fitbit Blaze review

Next up is the exercise tracking. With dedicated options for running, cycling, weights, treadmill, elliptical and open workout it appears the Blaze has all the bases covered. What's more, like the Fitbit Charge 2, the Blaze will automatically recognise exercise and track it automatically, which works well.

Bike and Run modes use Connected GPS to report distance, pace and all that jazz, while the rest essentially just monitor your heart rate and workout time to offer a calorific figure at the end of your session, and are identical in all but name.

Essential reading: How to actually use your fitness tracker to get fit

We had no issues with the Run or Bike accuracy when connected to the smartphone, but if you want to run without, it will guess the distance based on the movement of your arm. For us it registered an 8km run as 9.48km, which obviously had knock-on effects on the pace – making the data kind of useless. Tweaking your stride length in the app can help this a little, but still, it's not going to solve this problem entirely. But that's to be expected with any wearable trying to guess your distance without GPS.

Lots of runners will use a phone for music, so that's no big deal for them, but given the Blaze places much of its emphasis on its optical heart rate monitor, how does that fare?

Fitbit Blaze: Heart rate monitor

Fitbit Blaze review

Optical heart rate is getting better, but it still isn't going to challenge a chest strap, especially on a device like the Blaze which is now over a year old. If you want to do HIIT then buy a chest strap – end of. Incidentally, you'll have to use a different device, as the Blaze isn't compatible with ANT+ or Bluetooth straps.

The trouble is that 'useful' is a subjective term, and its meaning will differ from person to person. To try and work out what works for you, this is what the Fitbit Blaze can and can't do.

First up, 24/7 and resting heart rate tracking. We found the data to be spot on, and it aced a number of spot checks against our pulse when sitting down. The resting heart rate tracking – a superb measure of your improving fitness – was spot on, and we love the way it's tracked within the app. Gold star.

Essential reading: Why sleep is Fitbit's new obsession

During exercise, however, things get complicated. On a gentle jog we found the data to be useful, and stayed within 5bpm of a chest strap, straight out of the door.

However, as we upped the pace, things fell apart. As our heart rate rose up from 150bpm to 165bpm, the Fitbit remained static, locked to 150bpm. As we started to sprint the chest strap reported 170–180bpm, yet still the Fitbit stayed at 150. Later in the run it came back to the chest strap at around 165 as we started to cool down.

In our longterm test, the results were largely the same. On a light run, the Blaze capped out at 152bpm while our chest strap reported 160bpm, as we went faster the Blaze stayed put and the chest strap went up to 170bpm. On our way down, the chest strap was with us all the way while the Blaze exhibited some lag until we came down to 140bpm, when it started to catch up. Not great, so what gives?

Well, the Blaze's tracking can't really handle high intensity, and what's more, it suffers from a dreadful lag time, making its suitability for hardcore sessions non-existent.

The two graphs below show off some of the heart rate discrepancies. On the right is the Fitbit's heart rate monitor, on the left is the readout from a Wahoo Tickr Run chest strap.

Fitbit Blaze review

Things got worse in the gym, too. As we expected, twisting of the arm caused big drop-outs in heart rate tracking, which we discovered during the FitStar workouts. 30 seconds of press-ups got our heart rate sky high, yet the live readout dropped to below 100bpm.

We knew all this already, though. We knew that the Fitbit wouldn't match a chest strap. But coming back to our question: is the data useful or is it junk?

The Fitbit's resting heart rate tracking is great, and its optical heart rate monitor can colour your workouts and make calorific burn more accurate from your sessions – whether it's a big gym session, weekend run or walk to the bus stop.

There's also Cardio Fitness Level, which was released via software update well after release. The feature allows the Blaze to provide a look at your fitness level compared to other people your age and gender, by estimating your VO2 Max level. It uses a combination of resting heart rate compared to your heart rate while on a run of at least 10 minutes. It's a good measuring stick that also lets you quickly see how much weight loss and increased exercise can help improve your fitness level.

The Blaze is absolutely fine for beginners and improvers to take to the gym or out for a run, but it's not an adequate training tool for those looking to train within specific zones – despite this being a feature of the company's marketing for Blaze. If you want to get specific about which zone you're training in, neither the Blaze, nor any optical based device, is right for you.

Fitbit Blaze: FitStar

Fitbit Blaze review

A somewhat shoehorned addition to the Blaze is the set of guided FitStar workouts that live on the watch's menu system. The idea is that you can fire up a workout, and then follow it on the watch.

It's a great idea, and bolsters the Blaze's credentials as a 'fitness watch', even if at present there are only three workouts: Warm up, 7 Minute Workout and 10 Minute Abs.

We followed a couple, and were left with mixed feelings. On a positive note, the workouts are easy to follow, there's no interaction required, and they offer a way for Blaze users to do a structured workout in their own home, whenever they have time.

But is this really the best Fitbit could come up with?

Fitbit Blaze review

Despite being on a watch with sensors, there's no rep tracking. It doesn't keep score of your performance within the 30 second time slots for each activity and doesn't offer much incentive to do better next time. There are no levels of difficulty, no progression. It's totally undercooked.

Maybe we've been spoiled with Moov's 7 Minute Workout offering, which uses a sliding scale of 40 levels to offer a sense of progression as you're challenged to do more and more exercises in the allotted time. And each rep is tracked, so there's no wimping out. Compared to that experience, the FitStar stuff is Mickey Mouse.

Fitbit Blaze: Notifications

Fitbit Blaze review

When the Blaze first arrived, the only notifications it could display were text messages and call logs. That's it. Thanks to an update since then, you can now receive notifications from third-party apps, from social media apps like Facebook and Twitter to news apps from the New York Times and Wall Street Journal. Enabling the notifications are nestled into the notifications section of the companion app, so you'll have to dig in their to get them going after you set up your Blaze.

While the Blaze can display notifications from third parties now, you can't really do much with them. They're just there to tap you on the wrist and let you know that you'll have to get your phone out when you have a chance.

While our notifications suffered outages in our initial review, our longterm testing showed no problems. We received notifications for all of our incoming alerts, so it appears that Fitbit has addressed this problem via a software update.

Fitbit Blaze: The app

Fitbit Blaze review

The Blaze feeds into the same app as the rest of the Fitbit family. It's a great ecosystem, full of social challenges, badges to earn and it's well laid out and easy to use.

Each day is 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.

Tapping the heart rate score is most effective, and you'll see your resting heart rate plotted over time. Give it three months and you should see a nice downward curve as you get fitter.

Amazon PA: Fitbit Blaze

The app has, since the initial review, gained a new Guidance tab built around FitStar exercises and a Notifications tab that collects all your fitness accomplishments and messages in one place. There's also Sleep Insights, which offers guidance around your sleep patterns. Thus far, most of this guidance has been generic but as we said, this should improve over time.

Overall, the Fitbit app is one of its strong points. Easy to use and clear, it offers enough data without feeling overwhelming, and unlike some of the competition, the sync between smartphone and watch is pretty bulletproof, - we never experienced connection issues.

Fitbit Blaze: Battery life and waterproofing

Fitbit Blaze review

Fitbit promises five days of battery life from the Blaze, which was absolutely borne out in our tests. Even with some tracked workouts, the Blaze expired exactly five days after our initial charge. It's pretty impressive given the smart notifications, bright OLED screen and the svelte build that leaves little room for a battery.

Fitbit Blaze: One year on

The Blaze lives in a different world now. The Alta HR and Charge 2 have come along with sleeker designs, making the Blaze look a bit long in the tooth. In terms of hardware features, the Blaze lacks the Flex 2's waterproof design and the GPS abilities of its elder "fitness watch" brother, the Surge - which is particularly felt with other GPS wearables flooding the market. In other areas, the Blaze outdoes its newer siblings. Its larger display is better for reading messages, and it's also got third-party notifications in its corner. Though compared to other smartwatches, especially the Apple Watch and Android Wear 2.0 devices, its notifications are lacking, as you're unable to take actions on many of them.

Some of the Blaze's new features, like Sleep Stages and third-party notifications, are handy, while others, like Relax guided breathing, may not be such a big deal for you. However, those new features don't make up for its shortcomings, which still include a so-so heart rate tracker, basic guided workouts and a lack of GPS. Still, Fitbit's first proper smartwatch can't be far off now...

How we test

James Stables


James is the co-founder of Wareable, and he has been a technology journalist for 15 years.

He started his career at Future Publishing, James became the features editor of T3 Magazine and and was a regular contributor to TechRadar – before leaving Future Publishing to found Wareable in 2014.

James has been at the helm of Wareable since 2014 and has become one of the leading experts in wearable technologies globally. He has reviewed, tested, and covered pretty much every wearable on the market, and is passionate about the evolving industry, and wearables helping people achieve healthier and happier lives.

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