Fitbit Charge 4 review: a powerful fitness tracker with one problem

As good as it gets for the fitness tracking band
Fitbit Charge 4
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Fitbit’s newest fitness tracker – the Fitbit Charge 4 – brings with it GPS and a new focus on heart rate monitoring. And not before time.

The Charge range is Fitbit’s all-action fitness tracker range, a step up from the Inspire HR, with sports tracking modes, music controls and a bigger screen. It’s the best of Fitbit, in the form of a fitness band.

Before diving in with our comprehensive review, let’s preface everything by quickly summarising the Fitbit Charge 4: it’s the most advanced fitness tracking band from the company that does fitness tracking the best. So, by default, it’s the best fitness tracker available to buy today.

But beyond adding GPS, Fitbit hasn’t bothered to make the Charge 4 absolutely the best it can be by improving the size, design or screen. It's easily the market leader, because the fight is in smartwatches now – we can't see anyone bothering to truly compete against the Fitbit Charge 4 in terms of sensors or features.


The Fitbit Charge 4 tells us if you want the best fitness/wellness tracking experience, you should buy a smartwatch. Many of these new features will soon land on the Fitbit Versa 2 – but beyond the dated hardware, the Charge 4 does possess a potent mix of features that still makes it unique.

Fitbit Charge 4 key features:

  • Steps, heart rate and sleep tracking
  • GPS built in
  • Blood oxygen tracking
  • 7 day battery life
  • Fitbit Pay
  • Notifications
  • Spotify controller
  • VO2 Max tracking
  • Workout tracking modes

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Fitbit Charge 4: Design

Fitbit Charge 4 design

The Charge 4 lives in the body of the Charge 3, nothing has changed in that regard. That’s not necessarily a bad thing, it’s still a decent looking device that’s comfortable to wear – and while it could be a little thinner, that’s fine by us. What’s more, there are tons of cheap Charge 4 bands out there you can pick up.

But the same body lands you the same screen – and this is the first gripe, because it’s pretty bad.

In 2018 when the Charge 3 first landed it did the job, but in 2020 the 60x100 pixel touchscreen is really basic. It’s bland, pixelated and dull, and hard to read in bright conditions. What’s more, it’s not even always-on and the wrist raise action needs to be pretty deliberate, and often lets you down.

Can power management be that tight that Fitbit can't keep this monochrome display on all the time? We should also add that battery life, in terms of basic use, is still seven days which is unchanged from the Charge 3.

Fitbit Charge 4 side profile

This is something we feel should have been improved on with over two years of innovation.

The touchscreen controls work fine, and the haptic button on the side will wake the screen, send you home, and resume/pause workouts.

The band itself is nice and comfortable and the buckle is secure, and the device is still water-resistant to 50 metres, and supports pool swimming.

Fitbit Charge 4: GPS, running and workouts

Fitbit Charge 4 front on

Pretty much all the changes in the Charge 4 are with sports tracking, so we’ll get onto that first.

By default the sports tracked by the Charge 4 include running (GPS), biking (GPS), swimming, treadmill, outdoor workout (GPS) and walk (GPS). That’s because the Charge 4 can only hold six shortcuts to workout modes on the device itself.

However, you can add a pretty complete amount of sports ranging from HIIT, circuit tracking, spinning, weights and even golf by heading to the Fitbit app and choosing Account > Charge 4 > Exercise Shortcuts and swiping left to delete a sport and then replacing it with one from the list.

The GPS workouts get distance, pace, speed, time, heart rate – while workouts such as weights, for example, are about time, calories, heart rate and not rep counting or anything crazy specific. It’s useful these are named, however, as it’s good to see workouts correctly tagged in the app.

Fitbit Charge 4 main shot

Running has always lived on the Charge series but it previously required a smartphone to come along for GPS – and that does create issues of accuracy depending where that phone is placed. Now it can do that alone. We ran multiple times with the Charge 4 and found accuracy to be spot on using GPS (we compared results against both an Apple Watch and a Garmin running watch).

Battery, however, was more of an issue. Quoted battery life is five hours on GPS, which is just not representative of our testing. We drained the battery around 30% on a 45 minute run, on three occasions. That’s not brilliant, so make sure you have over 50% before heading out for a run.

Runs are recorded in the Fitbit app, and are pretty nicely presented. You can see your split times per kilometre or mile, and your heart rate zones, which we’ll come onto next. Fitbit’s not amazing for runners, because ALL exercise is logged, so you’ll find a lot of random auto-tagged walks in amongst your runs – and there’s no real focus on how you’re progressing as a runner, just how that exercise is affecting your health.

Fitbit Charge 4 running stats

That’s probably a good way of explaining who the Charge 4 is aimed at – if you run to be healthy, this is a good mix of features. If you run competitively, and by that we mean you’re interested in your performance as a runner, there’s not enough here for you.

You can always opt to pair Fitbit with Strava, then you get the best of both worlds.

A word on auto-tagging: runs and walks were routinely auto-detected and logged in the app, although we did a 45 minute HIIT session and while heart rate zones were logged, and we got the requisite Active Zone Minutes, it never appeared as a tagged exercise.


Fitbit Charge 4: Heart rate

Fitbit Charge 4 heart rate SpO2 sensor

Just to start by going over old ground, the Charge 4’s heart rate accuracy is solid – but it will let you down at the highest intensity (as all optical monitors will). Across a number of steady runs, we were really pleased how it performed compared to a chest strap, even in the 190+ bpm range.

It suffered on very rapid rises and falls in heart rate on hill repeats – where it just couldn’t cope with the rapid surge in heart rate, and the Apple Watch Series 5 certainly handled that better.

You can see that in the comparative workouts below – where halfway through the run we stressed the device with three short sharp hill repeats. Chest strap tracks those quick rises, while the Charge 4 really doesn't get near them.

Otherwise, however, you can see an extremely close match between the two – even the surge in heart rate at the end, and rapid drop offs when resting.

Fitbit Charge 4 heart rate data comparison

Active Zone Minutes

Fitbit’s SpO2 sensor is on board, and all fired up, so you will see blood oxygen information logged in the app. You’ll find it in your sleep analysis, under Restoration.

But heart rate is now a larger part of the Fitbit Charge 4’s offering than before, with Active Zone Minutes now part of the mix. It’s replaced Active Minutes on the Charge 4 (the target used to be 30 minutes a day), and makes it more useful – although we do feel it will be harder for people to understand.

The premise is simple – the World Health Organisation and American Heart Association recommend 150 minutes of exercise per week, or 75 minutes of vigorous exercise.

Fitbit now uses heart rate zones to award these minutes to a goal: if you get into the fat burning zone for 1 minute you get 1 minute awarded.

Fitbit Charge 4 Active Zone Minutes test

Previously, this discriminated against more active people, who would get the same reward for a HIIT workout than someone for a brisk walk. So if you get into the Cardio or Peak zones, you get 2 minutes awarded for every minute of exercise.

What's more, you'd previously have to do ten minutes of activity to get receive any Active Minutes. But now if you elevate your heart rate for one minute you get one Active Zone Minute.

Zones are also calculated based on your personal heart rate data – using your resting HR as a measure of fitness, and your HR Max calculated by your age. This means the goal should be weighted to your fitness level, and will automatically adjust as you get fitter. That's super smart – and a great way of using the data Fitbit has to give everyone smarter goals.

But there's one minor gripe.

The WHO advice is a weekly goal, but on the Charge 4 it's presented among your daily ones. Active Zone Minutes metric says X of 22. Sorry, where’s 22 come from?

That’s because it’s the closest whole number to 7 days divided by 150 minutes of weekly exercise. But it’s a weekly goal not a daily one? That doesn’t matter – that’s how it’s presented.

Fitbit isn’t really set up for weekly targets. To find it you have to go to Active Zone Minutes on the dashboard and choose Week, then swipe left on the graph to see your Sun – Sat progress.

You can change your Active Zone Minutes goal, and have totally separate ones for the day and the week – and Fitbit has already made changes to make this clearer in the app.

That does improve the situation somewhat – but it will remain a daily goal on the wrist, no matter how you use the target. You can read our guide of how to use, change and view your Active Zone Minutes.

Fitbit Charge 4: Fitness tracking and sleep

Fitbit Charge 4 fitness tracking and steps

Up top we said that despite our annoyance that Fitbit hadn’t put its heart and soul into making the Charge 4 the best it could be, it was still the top fitness tracking band on the market.

That’s because Fitbit data is more compelling than most of its rivals – and a visit to the dashboard really puts you in touch with your data. While the Apple Watch Activity rings are probably the best daily goal visualisation, Fitbit does a better job at displaying your progress over the weeks and months.

Your current day is simply laid out at the top, then you can quickly see how much exercise you’ve done, your heart rate and resting HR, and brings like weight, water intake and food.

Dive into one and you can see progress over time. Sleep for example, is clearly shown as part of seven days, not in isolation. The graphs are all super clear – it’s a great app.

Fitbit Charge 4 sleep test data

Sleep tracking is right up there as the best in the business – and one of the few systems to add awake time into the mix. Tossing and turning makes up a big part of the nights, and you don’t get rewarded for that, so your sleep might be judged more harshly than other devices.

You get an overall score for your sleep, and if you use Fitbit Premium, you can see how that was calculated too, with breakdowns for Time Asleep, Deep and REM time and Restoration.

Without a sleep lab it’s really hard to say how accurate this is, but you can absolutely affect the numbers, and you can see the effects of things like alcohol and late nights. And that’s what it’s all about – Fitbit enables you to work on improving your sleep quality more than any other system we’ve used.

Female health tracking is part of the app, and you can track your cycle in pretty good detail (my wife had a look through the feature.) However, oddly you can’t tell Fitbit if you’re pregnant which seems a strange omission. It would also help color some data, an add an extra layer of usefulness.

Fitbit Charge 4: Smartwatch features

Fitbit Charge 4 notifications

The Charge 4’s large screen enables you to get notifications from your paired smartphone, and surprisingly, the 1-inch screen does a passable job at displaying them.

You will get alerts of calls and text messages, calendar updates. However, WhatsApp messages still aren’t supported, the logic for which is still beyond us.

Fitbit Pay is present, and still has patchy support for banks – although it’s got most of the big players in the US.

And now there’s dedicated support for controlling Spotify music playing on any of your devices (although not storing it). In the settings you can enable the Spotify app (it comes pre-installed but you have to add your sign in details). From there you can control playback by selecting songs from within a playlist, skipping forward and back and even controlling where music is played to from a list of Spotify Connect devices on your network.

However, you can’t control music when you’re recording a workout which almost seems like the effort was a waste of time. The one time you actually might want to go to the effort of controlling music on a 60 x 100 pixel display is when your phone is tucked away during a workout, but it’s not available.

What’s more, this only works with Spotify Premium. If you use a different service, you have zero controls of music.

Fitbit Charge 4: Value for money and rivals

Fitbit Charge 4 and Inspire HR side by side

So how does this stack up and what are your other options?

We’re going to assume you’ve discounted smartwatches as an option because of personal preference – or you’d be clearly looking at a Fitbit Versa 2 ($199), Apple Watch Series 3 ($199) or an Amazfit GTS ($149) to give the full gamut of price range.

The Inspire HR offers a more simplified experience, still with the great sleep tracking, but without exercise tracking, blood oxygen and GPS. And the Xiaomi Mi Band 4 is actually nicer looking, cheaper, but has no GPS and the app is inferior.

But really, for the full like-for-like of features, it’s only really the Garmin Vivosmart 4 (no GPS) or Garmin Vivosport (GPS but ugly and dated) that can really compete.

Fitbit Charge 4
Fitbit Charge 4



Fitbit Charge 4
By Fitbit
Still the best fitness tracking band for the active person, the Fitbit Charge 4 adds accurate GPS tracking to its roster of good heart rate insights, best-in-class sleep tracking and Active Zone Minutes. With this mix of features, it’s now pretty unique on the fitness tracker market. It’s still the best fitness tracking band around, because Fitbit’s ecosystem and analysis, plus the brilliant range of features make it so. But Fitbit’s decision not to improve the battery life, screen, interface, notification support or design probably means this is as good as it gets for this form factor. It could have been incredible – but it’s got enough to be the best.

Hit
  • GPS on board
  • Comfortable design
  • Accurate
Miss
  • Crummy screen
  • GPS drains battery hard