A fitness tracker is only as good as its data — and its data is only useful if you actually keep wearing it. We tested six top-selling trackers 24/7 for a full month: two on the treadmill, one through swimming sessions and all of them through typical work-and-sleep weeks.
Accuracy That Matters
Heart rate drift became the deciding factor. The best pick stayed within 3 beats per minute of a chest strap during interval training, while its step counts matched a lab pedometer within 1.5%. GPS phones and sleep staging were also cross-checked against a reference device each night.
Battery & Real-Life Comfort
Battery claims ranged from 5 to 14 days. In real use, the daily-charge models became a habit for about half the testers; the longer-lasting options removed that friction entirely. Comfort across sleep-tracking hours favored lighter straps without protruding sensors.