(Pocket-lint) – There was a time when Fitbit had nine activity trackers in its portfolio, though the company retired the Flex, Alta and Zip lines when it launched the Inspire family in 2019.

The Charge 4 sits at the top of the trackers, with the Inspire 2 below, succeeding the older Inspire and Inspire HR. There’s also the Fitbit Luxe to consider too, which sits inbetween. You can read how the Fitbit Luxe, Charge 4 and Inspire 2 compare in our separate feature. 

If you’re wondering whether the Fitbit Charge 4 or the Inspire 2 are right for you though, or whether to upgrade from Inspire or Inspire HR, here is how the trackers compare.

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Fitbit Inspire 2 vs Charge 4: Price

• Inspire:£69.99 / $79.95 / €79.95
• Inspire HR: £89.99 / $99.95 / €99.95
• Inspire 2: £89.99 / $99.95 / €99.95
• Charge 4: £129.99 / $139.95 / €139.95

The Fitbit Inspire 2 normally costs £89.99 in the UK and $99.95 in the US, which is the same as what the Fitbit Inspire HR cost when it first launched. The standard Inspire model without heart rate normally costs £69.99 in the UK and $79.95 in the US.

The Fitbit Charge 4 usually starts from £129.99 in the UK or $139.95 in the US, with the Special Edition models jumping up to £149.99 in the UK and $159.95 in the US. Accessories are available for all models.

Design

• Inspire 2/Inspire HR/Inspire: Waterproof, slim, plastic body, touchscreen display
• Charge 3/Charge 4: Waterproof, premium in design, large touchscreen display
• All models have interchangeable straps

The Inspire 2, Inspire HR and Inspire all feature a similar design, which is smaller than the Charge 3 and Charge 4. They also all opt for a plastic body over stainless steel, making for light, small and discreet devices with the Inspire 2 a little softer and rounder than the Inspire and Inspire HR overall.

The Inspire 2, Inspire HR and Inspire have a smooth silicone strap as standard, which is interchangeable and fastened with a buckle.

An OLED touchscreen display is present on the top of all the Inspire devices and there is also a singular button on the left for returning to main menu and quick access to settings. This button is physical on the Inspire and Inspire HR and inductive on the Inspire 2.

A heart rate monitor and charging pins sit beneath the Inspire HR and Inspire 2, with only the charging pins on the Inspire, and all Inspire models are water resistant up to 50-metres.

The Fitbit Charge 3 and Charge 4 are a little larger than the Inspire devices, making them more obvious when worn, though the Charge 3 and 4 have a more premium finish thanks to their aluminium bodies. They also have a slimmer profile than all the Inspire models.

A textured elastomer band is present as standard for the Charge 3 and Charge 4 and they have larger OLED touchscreen displays than the Inspire models, protected by Corning Gorilla Glass. They also have an inductive button to the left of their display like the Inspire 2, rather than a physical button like the Inspire and Inspire HR.

Interchangeable straps are present again and the PurePulse heart rate monitor sits in the same position on the underneath of the casing, but the Charge 3 and Charge 4 add an SpO2 monitor too. Like the Inspire models, they are also water resistant to 50-metres.

Features

• Inspire: Steps, distance, calories, active minutes, basic sleep
• Inspire HR: Steps, distance, calories, HR, active minutes, advanced sleep, VO2 Max, Connected GPS, swim tracking
• Inspire 2: Steps, distance, calories, HR, active minutes, advanced sleep, VO2 Max, Connected GPS, swim tracking, Active Zone Minutes
• Charge 3: Steps, distance, calories, HR, elevation, active minutes, advanced sleep, VO2 Max, Connected GPS, swim tracking, NFC
• Charge 4: Steps, distance, calories, HR, elevation, active minutes, advanced sleep, VO2 Max, Built-in GPS, swim tracking, Active Zone Minutes, NFC

The Fitbit Inspire models and the Fitbit Charge 3 and Charge 4 all measure steps taken, distance travelled, calories burned, active minutes and continuous heart rate, though the latter is not present on the standard Inspire, only on Inspire HR and Inspire 2. Automatic sleep tracking, silent alarms, Reminders to Move and hourly activity are all also on board all models though, along with smartphone notifications.

All models, except the standard Inspire, also offer advanced sleep stages and Sleep Score, while the Charge 4 also offers Smart Wake, which uses machine learning to wake you up at an optimal time.

All models also have Fitbit’s SmartTrack, which is a feature that allows trackers to recognise certain activities and record them in the exercise section of the Fitbit app in order for users to categorise them and see a more detailed account of what they have done.

The standard Inspire’s features stop there, while the Inspire 2, Inspire HR, Charge 3 and Charge 4 add several more, marking the biggest differences between these trackers aside from their size and appearance.

The Inspire 2, Inspire HR, Charge 3 and Charge 4 also offer Guided Breathing, Cardio Fitness Level (VO2 Max measurement), Fitbit’s Multi-Sport Mode, Goal-Based Exercise and swim tracking. The standard Inspire is waterproof but doesn’t offer swim tracking.

Smartphone notifications are also more advanced on the Inspire 2, Charge 3 and Charge 4 compared to the Inspire and Inspire HR, with the newer devices offering Quick Replies for Android users and the ability to answer and reject calls.

The Charge 3 and Charge 4’s displays will also show all of the metrics found in the app on the display, including hydration and female health tracking, while the Inspire models offer some but not all.

• Fitbit Charge 3 review

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The Charge 3 and Charge 4 also measure elevation. None of the Inspire models have an altimeter so they won’t measure floors climbed. In terms of GPS, the Inspire 2, Inspire HR and Charge 3 have Connected GPS, meaning they will use your phone to record a map of your running or walking route, while the Charge 4 has built-in GPS and Spotify control support, marking the biggest difference between it and the other Fitbit trackers being compared here.

The Charge 4 and Inspire 2 also have a feature called Active Zone Minutes which uses your personalised heart rate zones to track your effort for any energising activity, allowing you to earn credit towards the recommended 150-minute weekly goal for each minute of moderate activity in the fat burning zone and double the credit for vigorous activity in cardio and peak zones.

Last but not least on the feature front, the two Special Edition models of the Charge 3 don’t just offer different strap options, they also feature an NFC chip, meaning these models are both Fitbit Pay enabled, which the Charge 4 is as standard. None of the Inspire models have NFC.

The Inspire 2 claims to have a 10-day battery life. The Charge 3 and Charge 4 claim to have a 7-day battery life. The Inspire and Inspire HR models claim to offer a 5-day battery life.

• Fitbit Inspire HR review 

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Fitbit Inspire 2 vs Inspire HR vs Charge 4: Conclusion

The Inspire models aren’t as premium in their design as the Charge models, but they are quite a bit cheaper. The older standard Inspire model does the basics, but the extra money for the Inspire 2 is certainly worth it for all the extra features you get – heart rate, VO2 Max, connected GPS, swim tracking, double the battery life and a more refined design, to name but a few.

The Charge 4 is the most feature-rich device on this list and its built-in GPS will make it the clear winner for some. The Charge 3 only offers a few extras over the Inspire 2 with some extra function for smartphone notifications, more on-screen data, elevation data and NFC (standard in Charge 4, option in Charge 3), but it has a more premium design too. 

The decision will likely come down to your budget and which features are really important to you. The Inspire 2 is the model we’d recommend over the standard Inspire and the Inspire HR, unless you can find the Inspire HR much cheaper. It’s double battery life also makes it a good contender for upgrading.

The Charge 4 is the model we’d recommend for those after a slightly larger device and a more premium look with all the features of the Inspire 2 (except the few extra days battery life), along with a couple of extras including built-in GPS and Fitbit Pay as standard. The Charge 3 is worth considering if you aren’t bothered about built-in GPS however and you can find it quite a bit cheaper than the Charge 4.

• Which Fitbit is right for me?

Writing by Britta O’Boyle.