The questionLeonardo da Vinci drew sketches of a prototype pedometer than 500 years ago. He never managed to make his design a reality, but today there are smartwatches and fitness trackers that claim to count your steps and tell you how you’ve slept, the number of calories you’ve shifted, if you’re stressed, and even if you need to sit down or stand up. But which ones are worth buying?

The basicsA team ofWhich?experts tested 97 devices. The cheapest was a £19.99 Smart Band from Xiaomi and the priciest was a £719 Apple Watch Ultra.

The methodTo measure accuracy, theWhich?experts wore each product while doing various tasks – walking upstairs, loading the dishwasher, going for a run – then compared its step count against a reference counter. They took the trackers to woodland areas to see if the GPS coped with signal, plus they monitored the battery and how heavy and comfortable they were. The trackers also underwent a privacy and security test.

The thing to rememberUnlike other recommendation services,Which?buys products before testing them, meaning no relying on freebies, and no biased results.

See the full range of expert reviews at which.co.uk/fitnesstracking

BEST BUDGET

Screen size43.5mm

CompatibilityiOS 12+, Android 8+

Battery lifeUp to 17.5 days

What works?The price, firstly. This is great value. Plus testers also thought it was comfortable, very easy to use and terrific at tracking casual exercise.

What’s the catch?There’s no GPS; outdoorsy types might be disappointed.

BEST MID-RANGE

Screen size50mm

CompatibilityiOS 14+, Android 7+

Battery lifeUp to ten days

What works?Loads. This was theWhich?product of the year for 2025. It has an accurate heart-rate monitor, great GPS tracking, is comfy, easy to use, and has good screen quality.

What’s the catch?You can link it to your phone and take calls, but the sound quality is a bit iffy.

BEST PREMIUM

Screen size44mm

Battery lifeUp to three days

What works?Even though this is the cheapest of all Apple watches, it still uses much the same tech as newer, pricier models. Testers said it is fantastically accurate and has a high-quality screen.

What’s the catch?It only works with an iPhone. And it’s missing some of the advanced features of pricier Apple watches.