We use cookies to allow us and selected partners to improve your experience and our advertising. By continuing to browse you consent to our use of cookies. You can understand more and change your cookies preferences here.

Coronavirus Read our latest advice
Reviews based on facts
Our rigorous tests find the facts, and our impartial reviews tell you the truth about how products perform. First month £5, then £9.99 per month, cancel anytime.
Try Which?
1 October 2020

How to buy the best fitness tracker

When shopping for a fitness or activity tracker, should you buy Fitbit, Garmin, Huawei or Samsung? Our guide can help
CW
Christina Woodger

The right activity tracker can provide you with an accurate, comprehensive and easy-to-understand view of your health, whether you’re running, cycling, swimming, measuring heart rate or just keeping an eye on your steps.

But paying for features you won't use, or for a device that's not designed for your type of exercise, is a common mistake. Our guide can help you settle on the perfect wearable so you can track your fitness and activity with a device you can trust. 

Browse our reviews of the best fitness trackers to see who came top in our tests.

Video: How to buy a fitness tracker

How much do fitness trackers cost?

You can buy a tracker for less than £15, or you could pay close to £250. But our testing has shown there’s little correlation between price and accuracy. 

It’s absolutely possible to pick up a great, affordable fitness tracker if you don’t mind missing out on some more advanced functions, but it is risky to shop at the cheap end of the market. For a selection of budget-friendly options that impressed in our tests, read our guide to the best cheap fitness trackers.

Fitness tracker features to look out for

Some fitness or activity trackers pack in a wide range of sensors to track everything from steps and heart rate to your exact location and even the intensity of sunlight, to let you know when it’s time to reach for the sunscreen. This can result in more detailed feedback, but as revealed by our tough tests, not every device is accurate.

On top of that, having too many sensors can reduce the battery life of your device or make it more complicated to use (we rate ease of use in our tests too), so it's important to get the right balance. 

Step tracking

A pedometer is the most basic sensor, and one you’ll find in any activity tracker. This will count your steps and can often capture distance, too, based on an estimation of your stride length. We put the step counter through its paces in our tough lab test and check the accuracy.

Built-in GPS

If your wearable has built-in GPS, it can track distance more accurately – as long as the GPS works well and doesn’t drop the connection. Many fitness trackers can be paired to your mobile phone to make use of your phone’s GPS, but built-in GPS is useful if you want to jog or cycle without carrying your phone.

Heart-rate monitoring

A heart-rate monitor is another option worth considering. This, as you might expect, will measure your heart rate throughout the day. It will report on your average heart rate, and periods of peaks and troughs – useful for tracking improvements in your fitness. It can also be used to measure VO2 max (the maximum rate of oxygen consumption), which can be great for climbers, people preparing for a particular event and athletes. 



Again, accuracy is important here, and this can vary a fair bit between different makes and models. We rate this as part of our lab tests too, to find good trackers that don't miss a beat.

Sleep tracking

Most trackers will keep an eye on your sleep, including motion sensing to see whether your sleep is disturbed, and a measure of REM, light and deep sleep. A smart alarm feature means your tracker will pick the optimal time in your sleep cycle, that’s close to your alarm, to wake you up. If you're interested in sleep tracking, we have a dedicated guide on how to track sleep with a smartwatch or fitness tracker.

Water resistance

Typically, if your fitness or activity tracker is rated for water resistance, there will be a list of obscure letters and numbers to reference how well protected it is against water. For example, an IP68 rating means that the device can be immersed in water at a depth of a metre or more, for a set period of time. An ATM rating is also important; a 1 ATM rating or higher means the device is water resistant up to 10 metres of pressure or higher. The pressure is important because, while you can take the wearable down to a certain water depth, if you sprayed the watch with a high pressure hose, it may not survive the experience. 

Third-party apps

If you already use an app on your smartphone or wearable, such as Strava or running app Map My Run, you won’t want to lose access to your data or the in-depth analysis dedicated apps can offer. Smartwatches are more likely to offer compatibility here, allowing you to pair with app services and sync the data from your wearable. 

Music

If you want to listen to music on your run without taking multiple devices out with you, look for a smartwatch that has built-in storage to store your tunes. You'll need a Bluetooth headset as well though. Music management is not a feature that's commonly found on activity trackers, so head over to our smartwatch reviews to browse all the models we've tested.

Fitness trackers are a great way of recording progress in a home gym, as well as outside. Read our exercise equipment buying guide for more on setting one up. 

How important is fitness tracking accuracy?

Depending on how seriously you're taking your exercise regime, accuracy might be quite high on your list of priorities. We test trackers to see how accurate they are at measuring steps, distance, calories, and heart rate, and take consistency into account as well - if a tracker is accurate on some days but not on others, you won’t know whether you’re improving. 

To find out more about fitness tracker accuracy, and see how the models we've tested perform against each of these measures, read our guide on fitness tracker or smartwatch accuracy.

How long do the batteries last?

Using your wearable could become irritating if you find yourself needing to charge it too frequently. Generally, activity trackers have the advantage over smartwatches here – they're simpler devices with smaller screens, so won't drain as fast. 

Most activity trackers have a battery life that ranges from a couple of days to a couple of weeks. Some models use coin-cell batteries, like a watch, and these will last several months before needing replacing.

Smartwatches, on the other hand, may need charging every day under heavy use.

All the wearables we test are measured for battery life in our labs. Browse all our fitness tracker reviews to find the perfect combination of features and longevity.

The best overall fitness trackers

Below we've hand-picked some fitness trackers that work as great all-rounders, with impressive accuracy, comfort and a good range of features. 

Best fitness trackers

Sign up to reveal product image
77%
Best Buy
£124.99
Reviewed

A great tracker for those who want to keep an eye on daily activity (rather than those who are super-serious about sports and want detailed metrics). It records steps, distance travelled and heart rate accurately, it's waterproof for use in the swimming pool, it looks attractive and it's comfortable enough to keep on your wrist all day. It doesn't have built-in GPS, though - so you'll need to take your phone out with you for it to track your running route.

Sign up to reveal product
First month only £5, then £9.99 per month, cancel any time
Already a member? Log in
Sign up to reveal product image
73%
Best Buy
£69.99
Reviewed

We love this fitness tracker. It tracks steps, distance and heart rate accurately, it's comfortable to wear, it's intuitive to use and it's waterproof for wearing in the pool. It doesn't have GPS, though, which is disappointing - meaning you'll need to keep your phone on you if you want it to track your running or cycling route.

Sign up to reveal product
First month only £5, then £9.99 per month, cancel any time
Already a member? Log in

Looking for a more specialised fitness tracker for measuring steps, heart-rate, running or swimming? Browse our guide to the top fitness trackers for 2020.

View all Fitness trackers