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 latest Charge 4 sits at the top of the trackers, with the Inspire and Inspire HR just below, replacing the Alta HR and Alta, as well as the Flex 2.

If you're wondering whether the Fitbit Charge 4 or the Inspire HR is right for you, or whether to upgrade from the Alta HR, here is how the three families compare.


Fitbit Inspire vs Charge vs Alta: Price

  • Inspire:£70
  • Inspire HR: £90
  • Charge 4: £130
  • Alta HR: £130

The Fitbit Inspire HR costs £89.99, while the standard model without heart rate costs £69.99. Accessories are available and they start at £19.99.

The Fitbit Charge 4 starts from £129.99, with the Special Edition models jumping up to £149.99. Accessories are available again and start at £19.99.

The Fitbit Alta HR is no longer available through Fitbit, though you might find it elsewhere. When it launched, it started at £129.99, with special editions costing more and specialist bands also costing extra.


  • Alta/Alta HR: Small and discreet, stainless steel body, tap display
  • Inspire/Inspire HR: Waterproof, slim, plastic body, touchscreen display
  • Charge 3/Charge 4: Waterproof, premium in design, large touchscreen display
  • All models have interchangeable straps

The Fitbit Alta HR has a very similar design to the Fitbit Alta, offering a slim build with a metal chamfered body measuring 15mm wide, a textured elastomer band and a 1.4-inch OLED tap display. It's small, discreet and subtle enough to wear with most clothing.

There are no physical buttons on the device, interchangeable straps that are swapped over by pushing back the clips on the underside of the device and the Alta HR is secured via a colour-matched buckle. The PurePulse heart rate monitor sits beneath the device, alongside the charging pins and it is splash and rain proof, but not swim proof.

The Inspire HR is a little larger than the Alta HR in terms of width, though smaller than the Charge 3 and Charge 4. It opts for a plastic body over stainless steel, making for a lighter device and once again, it's small and discreet. The Inspire HR has a smooth silicone strap as standard, which is also interchangeable and fastened with a buckle.

An OLED touchscreen display is present on the Inspire HR and there is also a singular button on the left for returning to main menu and quick access to settings. The heart rate monitor and charging pins sit beneath the Inspire HR like on the Alta HR, with only the charging pins on the Inspire, and both Inspire models are water resistant up to 50-metres.

The Fitbit Charge 3 and Charge 4 are a little larger again than the Inspire devices, making them a little 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 both the Inspire models and the Alta 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 and Alta, protected by Corning Gorilla Glass. They also have an inductive button to the left of their display rather than a physical button like the Inspire.

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.


  • Alta HR: Steps, distance, calories, HR, elevation, active minutes, advanced sleep
  • Inspire: Steps, distance, calories, active minutes, basic sleep
  • Inspire HR: Steps, distance, calories, HR, active minutes, advanced sleep, VO2 Max, Connected GPS, swim tracking
  • 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, NFC

The Fitbit Alta HR, 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. 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 Alta HR and standard Inspire's features stop there, while the 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 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 HR, Charge 3 and Charge 4 than the Alta HR, and even more so in the case of the Charge 3 and Charge 4, which both offer 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.


The Charge 3 and Charge 4 also measure elevation. Neither the Inspire or Inspire HR have an altimeter so they won't measure floors climbed, though the Alta HR will. In terms of GPS, the 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 also has 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 fat burn 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.

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


Fitbit Inspire vs Charge vs Alta: Conclusion

With the Inspire range brought in to replace the Alta family, many of the reasons to buy an Alta HR have been taken away. Unless you can find it cheaper than the Inspire HR, you prefer its design, or you really want elevation data and don't want the bigger Charge 3 or Charge 4 devices, there are few reasons to buy the Alta HR over the Inspire HR.

The Inspire models aren't as premium in their design as the Alta and Charge models, but they are quite a bit cheaper. The Inspire model does the basics, but the extra £20 for the Inspire HR is certainly worth it for all the extra features you get - heart rate, VO2 Max, connected GPS, swim tracking, 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 HR 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 HR is the model we'd recommend over the standard Inspire and the older Alta HR.

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 HR, 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.