Wearable Accuracy Leaderboards
Reviewed by Sameer Sontakey, Co-founder and Chief AI & Algorithms Officer at Sensor Bio. ChatPPG is independent and device-neutral; it is not a Sensor Bio product.
Rankings of consumer wearables built only from published validation studies against clinical references (ECG, polysomnography, pulse oximetry, indirect calorimetry). Devices are ranked only on the same statistic against the same kind of reference. We draw on 78 published studies, and every number links to its DOI.
Heart rate
Wearable Heart Rate Accuracy Leaderboard
In a 50-person ECG-referenced exercise study, the Polar H7 chest strap agreed best with ECG (concordance 0.996), followed by Apple Watch (0.92). Wrist-worn optical devices were least accurate on the elliptical with arm levers.
HRV
Wearable HRV Accuracy Leaderboard
Against multi-lead ECG at rest, HRV4Training (4.10% MAPE) and Oura (6.84% MAPE) had the lowest rMSSD errors reported by Stone et al. (2021); the camera-based CameraHRV app had 112.36% MAPE.
Sleep
Sleep Tracker Accuracy Leaderboard
In a 53-adult polysomnography study (Miller et al., 2022), Somfit (65%, κ 0.52), Oura (61%, κ 0.43) and WHOOP (60%, κ 0.44) had the highest sleep-stage agreement. All six were valid for sleep timing, but none was strong at staging.
SpO2
Smartwatch Blood Oxygen (SpO2) Accuracy Leaderboard
In 36 people with COPD at rest, Garmin Vivosmart 4 (RMSE 3.3%) and Apple Watch Series 7 (RMSE 3.5%) had similar error versus a pulse oximeter. Both overestimated SpO2, and the authors advised against using them during pulmonary rehabilitation.
AFib
Smartwatch AFib Detection Accuracy
The Fitbit Heart Study reported a 98.2% positive predictive value for concurrent AF; the Apple Heart Study reported 0.84. These used different definitions, so they are listed side by side, not ranked.
VO2max
Smartwatch VO2max Accuracy
In lab tests against indirect calorimetry, three Garmin models estimated VO2max with mean absolute percentage errors of 7.05% to 7.9%, and three Apple Watch studies found 13.2% to 15.79%. Pixel Watch 3 recorded 8.65% in a Google-funded study. Ultrahuman has only a company-written preprint.
Calories
Smartwatch Calorie Accuracy
No wearable counts calories accurately. Against indirect calorimetry, Shcherbina 2017 found no device with an energy expenditure error below 20%, and two later studies reported coefficients of variation of 8.0% to 34.5% for Apple, Polar, Garmin and Fitbit watches.
Download the wearable accuracy table (CSV)
Every leaderboard row with study, DOI, reference standard and sample size. We'll email you the link.
Methodology
We include a number only if it appears in the cited paper and the DOI resolves on Crossref. Rankings only compare results that use the same statistic against the same kind of reference, and each one shows how many studies and participants it rests on and whether the maker funded the work.
The full data, with the exact quote behind every number, is in the wearable accuracy database (CSV and JSON).
Many results come from older device generations, and newer models may perform differently until they are independently re-tested.