How many steps a day do you actually need?

What the studies we have published say — strongest evidence first. Every claim below links to the paper it came from.

1. Across 65 studies of wrist-wearable activity trackers, the Fitbit Charge measured steps with under 25% error and the Apple Watch measured heart rate with under 10% error, but energy expenditure was off by more than 30% for every brand tested.

   well supported · human data

   A trustworthy overview: a sweep of all 65 studies on wrist trackers in the general population. The studies measured accuracy so differently that results could not be combined into one number, so device comparisons are informal rather than head to head.

   Read the breakdown →Accuracy and Acceptability of Wrist-Wearable Activity-Tracking Devices: Systematic Review of the Literature. J Med Internet Res 2022

2. Among 442 users of a smart ring, the device's "cardio age" estimate correlated with sleep efficiency, REM sleep, sleep duration and daily steps, measures not fed into the algorithm, and 82.6% of users were rated younger than their actual age. All the authors work for the company selling the feature.

   preliminary · human data

   Retrospective observational analysis of 442 self-selected ring owners over 12 months, run entirely by employees of the company that sells the feature; correlations were weak (around r = -0.2) and no laboratory fitness comparison was reported.

   Read the breakdown →Wearable-derived cardiovascular fitness age and its lifestyle correlates in 442 adults. Front Digit Health 2026

This page collects what our published, cited studies say; it is information, not medical advice. Have a different question? Ask it here.