Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

We outline the differences between these very similar devices
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Fitbit’s got a new fitness tracker in town – and the Charge 4 is the best of the company’s technology in one fitness band.

But it's not too different to the excellent Fitbit Inspire HR in places - and we've heard from readers wondering exactly which fitness tracker they should choose.

The Fitbit Inspire HR retails for but you can pick it up cheaper if you wait for a sale. The Fitbit Charge 4 in comparison retails for , and is unlikely to see a price cut anytime soon. You can see a full comparison of Fitbit devices in our full buying guide.

Both have an optical heart rate sensor, a screen and share many of the same features? So which are you supposed to choose? Well, the good news is that for many people, the cheaper Fitbit Inspire HR will be more than enough – and save a bunch of cash in the process.

So let’s compare what you get – and which is right for you.

Compare reviews: Fitbit Charge 4 review | Fitbit Inspire HR review

Charge 4 vs Inspire HR: Build/design

Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

The first major difference between The Inspire HR and the Charge 4 is size. If you’re primarily concerned with the size of the device on your wrist, then the Inspire HR will suit your needs.

The Inspire HR measures half the width of the Charge 4 (22.7mm vs 12.6mm) and weighs 20g rather than 30g. It’s really is barely noticeable on the wrist and much easier to sleep with too.

But of course, there’s a pay off. The screen dominates the front of both bands, so that display is much smaller on the Inspire HR. The 1 x 0.6-inch screen is enough to show off your stats, but can’t convey the same detail on goal progress and notifications as the 1.57-inch screen of the Charge 4.

Both screens are pretty low grade, low resolution grey-scale – and neither are always-on, so you need to raise your wrist.

New model: Fitbit Inspire 2 review

That also feeds into things like workouts, where the Charge 4 will show live stats from sessions – while you get minimal feedback from the Inspire HR.

Both devices feature hot-swappable bands and there are plenty of third party Fitbit straps out there to choose from – and plenty on the Fitbit Store.

Charge 4 size

  • 35.8 x 22.7 x 12.5mm
  • 30g
  • 1.57-inch grayscale touchscreen OLED
  • Up to seven days, 5 hours continuous GPS use

Inspire HR size

  • 37 x 12.6 x 12.9mm
  • 20 grams
  • 1 inch x 0.6 inch grayscale touchscreen OLED
  • 5 days battery

Charge 4 vs Inspire HR: Fitness/activity features

Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

The feature sets across the two devices are actually a lot more similar than many realise – and this means that many people would actually be equally well served by the cheaper Inspire HR.

So let’s cover off the similar features.

Both devices track steps, sleep and 24/7 heart rate – which feeds into the logging of resting heart rate. However, only the Charge 4 will track floors climbed.

The main difference here is that the Fitbit Inspire HR tracks active minutes while the Charge 4 has change to track Active Zone Minutes – a new metric. Active Zone Minutes require you to elevate your heart rate into the Fat Burn zone – and you get double credit for time in Cardio or Peak zones. Accruing an Active Zone Minute is tougher on the Charge 4 but better suited for ensuring you’re getting the WHO’s recommended 150 minutes a week.

Tracker top picks: Amazfit Band 5 v Fitbit Charge 4

Both devices feature workout tracking, and can be manually set to capture a particular type of exercise. Largely these are just time, duration, heart rate and calories, but it does mean the exercise type will be logged in the Fitbit app.

Both devices will auto-detect some forms of exercise too – including outdoor walks.

Both devices use Fitbit’s top-level sleep tracking, and you get Sleep Score as well as the monitoring of sleep stages, such as deep, REM and light sleep. However, as we’ll outline below, only the Charge 4 will monitor Estimated Oxygen Variation.

Both devices will also estimate Cardio Fitness Score, which is Fitbit’s name for VO2 Max.

So what do you get for the more expensive Charge 4?

Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

Firstly, it has GPS built in so it will track outdoor runs and cycles. The Inspire HR will use Connected GPS, which piggy-backs your phone for location data. That’s a good stop gap but runners should absolutely choose the Charge.

The Charge 4 has an SpO2 sensor so it will add Estimated Oxygen Variation when sleeping – which can highlight some sleep conditions including sleep apnea.

Fitbit Inspire vs Charge 4: Notifications

Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

Both will also show notifications from your smartphone – although only calls, calendar and SMS messages. Third party messaging such as WhatsApp isn’t supported.

However, you can do quick replies from the Charge 4 only.

Thanks to its larger battery the Charge 4 will last longer away from its power cable than the Inspire HR.

The Inspire HR will last around 5 days on a single charge, while the Charge 4 will do seven days with fairly heavy use including some tracked workouts.

And the Charge 4 has built-in Spotify controls, that let you manage playback from your Spotify Premium account from the wrist (although not storage, or direct listening from the device itself.

Choose the Fitbit Charge 4 if…

Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

If you’re a runner or cyclist then the Fitbit Charge 4 is a no-brainer – the addition of GPS makes it immensely powerful, and the addition of VO2 Max, Active Zone Minutes and heart rate metrics mean that workouts are well supported by other wellness features. If you want the maximum amount of data Fitbit can provide, this is for you.

Choose the Fitbit Inspire HR if…

Fitbit Charge 4 vs Inspire HR: Reading this guide could save you money

The Inspire HR is a super-charged fitness tracker at a great price – packing some of Fitbit’s best features (sleep, heart rate and goal based analysis) into a slim, feature rich tracker. The fact that its workout tracking matches the Charge 4 is under-appreciated in our opinion.

Charge 4 vs Inspire HR comparison table

Inspire HR Charge 4
Size 37 x 12.6 x 12.9mm 35.8 x 22.7 x 12.5mm
Weight 20g 30g
Swap straps Yes Yes
Screen size 1.0 x 0.6-inch 1-inch
Steps Yes Yes
Yes Yes
Active mins Yes Active Zone Minutes
GPS Via smartphone only Yes
Heart rate Yes Yes
VO2 Max Yes Yes
SpO2 No Yes
Notifications Yes Yes
Workout tracking Yes Yes
Battery life 5 days 7 days
Waterproof Yes Yes
Swim tracking Yes Yes

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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