‘I’ of the tiger: The best fitness tracker for iPhone in 2024

No other devices integrate as seamlessly with an iPhone as an Apple Watch. And, of the three current devices, we think that the Apple Watch Series 9 is the best fitness tracker for most people. It strikes a balance between features and price, offering more than the Apple Watch SE (2nd gen), and being considerably cheaper than the Apple Watch Ultra 2. It not only provides a comprehensive suite of health and fitness tools, but it also offers a wide selection of third-party apps, including the likes of Strava and Nike Run Club. 

All the fundamentals we'd expect from a good fitness tracker are here – with the well-known activity rings tracking your total steps, active calories burned, and workouts completed. There's also heart rate, sleep, blood oxygen and nighttime temperature tracking. An ECG app lets you take an on-wrist electrocardiogram to check for atrial fibrillation (a common form of irregular heartbeat). Built-in GPS is highly accurate, and ideal for tracking outdoor activities.

The Series 9 is also great for tracking a wide variety of workouts, including running, cycling, strength training, and swimming, among others. It also integrates easily with Apple Fitness+ - a curated selection of workouts from Apple – which will display your personal metrics on screen as you exercise.   

Our biggest bugbear is the slightly restrictive battery life, which means you'll typically need to charge this daily. In part, that's because this is, alongside being an excellent fitness tracker, one of the best smartwatches currently available. Pairing this to your iPhone is a breeze, making this perfect for anyone who wants comprehensive fitness tracking that's easy to use.

Of course, not everyone wants to part with hundreds of pounds to track their fitness. Our current favourite budget fitness tracker for iPhone is the Xiaomi Mi Smart Band 8. For a fitness tracker that has an RRP of just £34.99, it still serves up an impressive selection of metrics for you to track. You will, however, need to accept a couple of compromises. 

The 1.62-inch screen is bright and clear, and there are a few basic smart features – including music controls for your phone, a calendar, and weather forecasts. But it's fitness tracking that this is focused on, offering step and calorie counting, sleep and heart rate tracking, plus a few extras. We're impressed to see metrics such as training load, recovery time and VO2 Max estimates appearing on such an affordable device. One further trick up its sleeve is Pebble Mode. For runners, this lets you attach the tracker to your shoe via an attachment (sold separately) to get more accurate running data. This includes metrics such as stride length, stride frequency, and impact force.  
In terms of the compromises? The Mi fitness app isn't as polished as apps from other brands such as Garmin, Apple and Fitbit. And there are question marks about how accurate it is. But it will give you a great introduction to fitness tracking, and if you want as many features as possible at a bargain price, this is the tracker to go for.

We're big fans of Garmin fitness trackers at What's The Best, and our current pick as the best Garmin fitness tracker for iPhone is the Garmin Venu 3. As one of the best Garmin watches, it offers a few smart features, without compromising on Garmin's reputation for health and fitness tracking.  

The Venu 3 arguably comes closer to being a "true" smartwatch than any other Garmin device. You can download and listen to music from Deezer, Amazon and Spotify, as well as being able to make and receive calls on your wrist via a connected smartphone. You don't get all the apps that you'd find on an Apple Watch, but that isn't what Garmin was aiming for. 

Instead, you get an outstanding package of health and fitness tracking tools. Heart rate, step, sleep, blood oxygen and calorie tracking are here, plus many of Garmin's bespoke training and recovery tools. These include Body Battery, Morning Report, Training Load, and sleep coaching. There are training plans developed by experts, plenty of running metrics, and built-in GPS that's supremely accurate. It's also great that Garmin has added a wheelchair mode on this watch, which tracks pushes, rather than steps. 

It's a superb fitness tracker, and it also happens to look great too. The AMOLED screen is absolutely gorgeous, and the watch is stylish enough for you to wear when you're dressing up, or when you're hitting the gym.

The Fitbit brand is no stranger to highly usable wrist-based tech - and now it's owned by Google you get a lot of advanced data know-how too. Your iPhone's operating system will need to be iOS 15 or higher though, so check your iPhone before buying. The Charge 6 has the best health and fitness features of any Fitbit.

One unexpected feature of such a compact tracker is the ECG with irregular heart rhythm notification. For anyone who needs to closely monitor heart activity, the Charge 6 will be indispensable here – Google claims this is the most accurate heart-rate tracker they've ever built. But the health-centric features don't stop there - a Daily Stress Management Score will tell you how much stress your nervous system is under. And you won't forget the route you took after enjoying your routine, as it has GPS too. 

The usual smartwatch functions haven't been left behind though, as you can read texts and emails and track your socials via notifications. Plus, you get six months of Fitbit Premium included, which will unlock the Readiness Score feature. This analyses your stats and advises you on what sort of exercise you should be doing on that day. It's a useful insight, although we have reservations about paying for it once your free trial period ends.  A seven-day battery life and water resistance of up to 50m finish the package off nicely. 

Digital Writer Jack Barrell has first hand experience with the Fitbit Charge 6, specifically paired with an iPhone. Here's how he got on with it: "I've not often been so consistently pleased with a fitness tracker as I have with the Charge 6. It's a top-notch fitness companion thanks to how committed it is to your personal goals and progress. What also goes a long way is just how satisfying and intuitive the Charge 6 is. Productive notifications, graphics, and vibrations give you a well done or a nudge of encouragement so you get the most out of your days.

It's not short of high-end fitness tracker features either, all of which work excellently too. Over 40 exercise modes makes you feel spoilt, heart rate monitoring is exact, and sleep tracking can really offer some food for thought. As an iPhone user, I have no complaints about it either. At this price, there's little else out there offering such value."

If you want a high-quality fitness tracker without breaking the bank, then the Garmin Forerunner 255 is a worthy candidate. As a slightly older mid-range model, having been superseded by the Garmin Forerunner 265, it has dropped significantly in price. We've seen it available for not much more than £200, making this something of a bargain.

It doesn't miss out on much in terms of features, tracking sleep, stress, steps, calories, and lots of different activity types. There's also Garmin's Body battery, Fitness Age, VO2 Max estimate, and recovery status metrics to add to the mix. Excellent GPS tracking means it's great for tracking runs, walks and bike rides, too. The single biggest compromise is the screen, which is a duller memory-in-pixel display, compared with brighter AMOLED screens on newer devices. But other than that, it's a great device, available for a relatively low price.

The Garmin Forerunner 255 was reviewed by Senior Tech Writer and fitness tech expert Steven Shaw. Here are his thoughts: "This watch is far more than ‘just’ a running watch. The comprehensive health and fitness metrics it checks make this a superb all-round fitness watch. It’s comfortable, easy to use, and the Garmin Connect app is, in my view, one of the very best fitness apps out there."

"The highly accurate GPS, excellent battery life and wide range of sports that it can track make this a viable choice for anyone who enjoys keeping fit. The Forerunner 255 doesn’t have all the features of the most advanced (and more expensive) Garmin devices. Personally, I didn’t feel there was anything missing that I desperately wanted. Garmin’s Training Readiness score was perhaps the most obvious omission, but there was more than enough to keep me happy."

Having been around since the 1970s, Polar has a well-established reputation for its heart rate monitors and fitness tracking sports watches. The Pacer Pro was released back in 2022. And while it isn't the newest and shiniest watch in Polar's collection, its competitive price, accurate data tracking and reliable performance make this a brilliant fitness tracker for iPhone users.

Heart rate, sleep, calories and steps are all tracked, while built-in GPS is accurate – although it can take a little while to form a reliable connection. If you are going outdoors, there are a few navigation tools to help you find your way. There are additional metrics too, including your Nightly Recharge score, a Boost from Sleep score, and the watch can even make suggestions about what workouts to do based on your metrics. Guided workouts even include animated stick figures to help show you what to do.

Steven Shaw tested the watch. In his Pacer Pro review, he wrote: " There’s a lot to like about the Polar Pacer Pro. Plenty of health and fitness tracking tools, and a respectable level of accuracy in most areas, make this a solid, reliable watch. For anyone who wants to focus on sports performance over smartwatch features, this device does exactly what you’d be looking for."

"To see any trends, or get deeper insights into any of your metrics, you’ll need the Polar Flow app. And while I don’t like the layout quite as much as the Garmin Connect app, I was impressed by the depth of insights that are available. I felt that everything was clearly presented, and if you aren’t sure what the data means, a little “I” icon gives you more information to explain exactly what you’re looking at." 

"While it doesn’t have every metric of the most modern devices, it is nonetheless a package which has almost everything for all but the most serious of athletes. I certainly didn’t feel there were any glaring omissions."

If you simply want the best Apple Watch of all, and don't mind so much about the price tag, then the Apple Watch Ultra 2 is the one to go for. It has everything you'll find in the Apple Watch Series 9, plus a few extras that mean that the price tag is significantly higher – the RRP starts at £799.

But in return for all your gold coins, you're getting Apple's most advanced watch, that's built to withstand tough outdoor conditions, scuba diving, and water sports such as jet skiing. It's clearly a different beast to non-Ultra Apple Watches. It sports a titanium case, and the Retina display goes much brighter than those other devices. The battery is significantly larger, although you'll still struggle to manage more than a couple of days between charges.

Crucially, as well as being suitable for a wider variety of sports and activities, the Apple Watch Ultra 2 doesn't skimp on other fitness metrics. ECG and heart rate data, sleep, blood oxygen, and nighttime temperature tracking are all available. You also get the same step, active minutes and calories monitoring found on other Apple Watches. This one even gives you a nudge if it thinks your cardio fitness is on the low side. Built-in GPS is also excellent. 

Simply, this is the best of everything that Apple has put into a smartwatch. The price tag means it isn't for everyone (hence why it doesn't top this list) but if you don't mind spending a bit more, you'll struggle to find better for an iPhone.

If you're looking to spend time in the great outdoors, then a fitness tracking watch that's tested to U.S. military standards for thermal, shock and water resistance is highly likely to appeal to you. Step forward, the Garmin Epix Pro, one of the most complete fitness tracking devices currently on the market.  

Yes, that military-grade testing gives some security for when you take the watch off the beaten track, while a fibre-reinforced polymer case and steel bezel afford some extra protection. There is a sapphire glass version which is a little bit more expensive than the standard model, but does offer added scratch resistance to the beautiful AMOLED display. 

As well as covering all the basics of heart rate, blood oxygen, sleep, steps, calories and activity tracking, the Epix Pro also includes Jet Lag adviser, stress tracking, heart-rate variability, health snapshot, nap detection, Body Battery and Morning Report. There are also a bunch of advanced metrics for runners, including Endurance Score, Hill Score, PacePro, ClimbPro, real-time stamina, training readiness, training status, and recovery time. There really isn't much missing from this in terms of health and fitness tracking.

Withings was the first company to introduce the concept of a hybrid smartwatch – in other words, a watch that looks like a traditional analogue timepiece, but with some of the useful tools you'd expect from a smartwatch or fitness tracker. The ScanWatch 2 is its latest and greatest timepiece, offering a stylish and elegant design, underpinned by plenty of health and fitness tools.

The ScanWatch 2 doesn't have built-in GPS, so you'll have to take your phone with you if you want to track runs, walks and bike rides. It's also got a very small digital screen, so reading notifications is much harder than on other devices. But a 30-day battery life is excellent, and if you want an elegant watch, reminiscent of a more civilised age, this stunner is well worth a look. 

Steven Shaw reviewed the Withings ScanWatch 2 for us. He said that, ""I would describe the ScanWatch 2 as a health monitoring device that also does fitness tracking. It's not as comprehensive as the best Garmin watches, for example. Those offer far more training and performance metrics than this. But, if you want some general fitness tracking, and some advanced health metrics, this watch will likely appeal."

"There's a lot that I really like about the ScanWatch 2. It's more feature rich than many alternative hybrid devices, and the design is among the best of the bunch. It's a simple, clean design that looks like a classic timepiece." 

"For some people, this will be close to the perfect smartwatch - not too smart, tracks plenty of health metrics, and has a few fitness features. And all while looking like a classic analogue watch."

Certainly worthy of being one of the best fitness trackers for kids, the Fitbit Ace 3 is a colourful tracker aimed at capturing the attention of your young ones. Apart from the fun virtual badges and cool avatars to choose from, even the fonts on the display are more exciting than the adult versions. The clock faces are animated too. And if your kids wear this every day, you'll be glad to know that it lasts up to eight days on one charge.

Also, if your child is prone to taking the odd swim or just getting soaked in the rain while they're out, the Ace 3 is water-resistant up to 50m. Some parental controls are on offer too, and that will help you make sure they're safe and well and even report whether they're getting enough rest. As fitness trackers go, despite the limited sensor types compared to adult versions, this is fun inside and out.

We've already highlighted the superbly integrated experience that comes from using an Apple Watch with an iPhone. But if the Apple Watch Series 9 and Apple Watch Ultra 2 are a little on the pricey side, the Apple Watch SE 2 is an excellent alternative. It doesn't offer quite as many health and fitness metrics as its two siblings. But it's around half the price of the Apple Watch Series 9, so for many, the trade-off between features and savings will be worth it.

Although it lacks the temperature sensor, ECG and blood oximeter of its senior, Apple has covered almost all the bases with its Apple Watch SE. It has the same 50m water resistance, as the Series 9, built-in GPS (this slimmer and lighter version of Apple's iconic wristwear also made it into our list of the best fitness trackers with built-in GPS). It still tracks calories, steps, and active minutes, as well as sleep and other metrics. The sensors are older than those used on the Series 9. But they still do a job.

It uses the same chipset as the Apple Watch Series 8. It's also up to 20% faster than the previous SE model. Aside from the usual Apple smart device features that all iOS users will be familiar with, we have a sleep monitor, GPS, and a heart rate monitor. The altimeter is always on, so you'll have one less thing to worry about as you scale new heights.

As you'd expect, you can take calls and reply to texts right from your wrist; as well as the usual music and podcast listening. Sync this with your iPhone, and you'll be on track to a better, more intelligent level of fitness.