フィットネストラッカー 比較

How to choose a fitness tracker in 2026

The Mars Score for fitness trackers weights fitness (50%), battery (30%) and design (20%). The category sits between basic step counters and full sports watches — if you mostly want sleep, steps, heart rate and 10–30 day battery without paying for multi-band GPS, a tracker is the right answer.

GPS or no GPS

has_gps is the dividing line. Trackers without GPS (Fitbit Inspire 3, Amazfit Band 7) clip to your wrist for 10–20 days but rely on your phone for route mapping. Trackers with GPS (Fitbit Charge 6, Garmin vivosmart 5) work standalone for outdoor runs at the cost of shorter battery.

Heart rate, SpO2 and sleep

Continuous HR and SpO2 sensors are now table stakes; sleep tracking accuracy varies wildly between brands. Whoop's 5.0 strap is the screenless outlier — it does no notifications and focuses entirely on recovery scoring. See Mars Labs for sleep-stage accuracy comparisons against polysomnography.

Battery in days, not hours

Battery is measured in battery_days because the entire category's value proposition is "set it and forget it for two weeks." Anything under 7 days starts blurring the line with smartwatches. Anything over 21 days is genuinely set-and-forget.

Water resistance and form factor

5 ATM (50 m) is the minimum useful rating for swim tracking. Below that, only splashes and rain. Display size (display_size_in) and weight matter less than they do on a smartwatch — most users hide trackers under a sleeve.

Glossary cross-links

For terminology like CADR, ATM ratings or burn-in see /en/glossary. For buying-context buying advice see Buyer's Guides.

How vsMars scores fitness trackers

Mars Score for fitness trackers weights fitness sensors highest because that is the category's whole purpose. See methodology for the per-spec weighting.