How to buy the best fitness tracker
By Christina Woodger
When shopping for a fitness or activity tracker, should you buy Fitbit, Garmin, Huawei or Samsung? Our guide can help
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.
In this article:
- How much do activity trackers cost?
- What features do I need?
- How important is accuracy?
- How long do the batteries last?
- The best overall fitness trackers
Video: How to buy a fitness tracker
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.
We've found a model costing just £20 that tracked steps with no error
It’s absolutely possible to pick up a great, affordable fitness tracker if you don’t mind missing out on some more advanced functions. We’ve found some great budget-friendly options in our tests – check out our best cheap fitness trackers.
Some fitness or activity trackers have as many as 11 separate sensors, to track everything from your 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. Having a variety of accurate, consistent sensors gives you more detailed and, in some cases, more accurate, data. But, as revealed by our tough tests, not every device has accurate sensors.
And having too many sensors can reduce the battery life of your device or make it more complicated to use. We rate every device in our tests to see how easy it is to use – check out our ease-of-use ratings before you buy.
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.
If your wearables has built-in GPS, it can track distance more accurately – as long as the GPS works well and doesn’t drop the connection, that is. 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.
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 useful for climbers, people preparing for a particular event and athletes.
During our lab testing, we put the accuracy of heart-rate monitoring to the test to ensure they don’t miss a beat.
Most trackers provide an ongoing record of your calorie burn. Models with heart-rate monitors usually loop in the heart-rate data to better estimate how many calories you’ve burned. However, the accuracy of calorie-burn data is largely dependent on how well the algorithm built in by the manufacturer interprets your fitness data. The presence of a heart-rate monitor doesn’t guarantee more accurate calorie-burn information.
105%We've found one tracker that reported double the number of calories burned
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.
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.
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.
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.
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.
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, largely due to the lack of a large screen, and additional features like pairing with a smartphone to monitor notifications.
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.
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
This slimline wrist fitness tracker is a proven Which? Best Buy. It tracks steps, distance and calories and uses SmartTrack to automatically recognise how you're moving around. The tracker is waterproof to 50m and has a built-in heart monitor. GPS isn't included, so you'll need to use your smartphone to track running routes.
This fitness tracker monitors steps, sleep patterns, heart rate and calories. Built-in GPS means you can track where you exercise, while a waterproof design makes it suitable for swimming in fresh water up to a depth of 50 metres. Once the device is synced with your smartphone, you'll get on-screen notifications for text messages, social media updates and emails. An impressive tracker with a good range of fitness features.
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.