Population benchmarks, measurement methodology, and percentile calculators — built on published research, not marketing copy. For people who already own a wearable and want to understand their numbers.
Explore Metrics Library Open CalculatorsDo you use Oura, Whoop, or Garmin? Start with the metric that matters most to you.
Oura → Whoop → Garmin → See all devices →Definitions, measurement methodology, normal ranges by age and sex, and which devices measure each metric — all source-cited.
The time variation between consecutive heartbeats. One of the strongest proxies for autonomic nervous system fitness.
View metric →Percentage of time in bed actually spent asleep. Clinical benchmark is ≥85%. Most wearables underreport this.
View metric →Maximum oxygen uptake during peak exertion. The single strongest predictor of cardiovascular longevity in published literature.
View metric →Beats per minute at complete rest. AHA defines normal as 60–100 bpm; highly trained athletes regularly register 40–60.
View metric →Slow-wave sleep drives physical recovery, immune function, and memory consolidation. Declines significantly with age.
View metric →Rapid eye movement sleep regulates emotional processing and procedural memory. Target: 20–25% of total sleep time.
View metric →Time from lights-out to sleep onset. Clinical range: 10–20 minutes. Under 5 minutes signals sleep deprivation.
View metric →Breaths per minute during sleep. Elevated baseline is an early illness marker tracked by Oura, Garmin, and Whoop.
View metric →Deviation from personal baseline during sleep. More useful than absolute readings. Key signal for illness and recovery.
View metric →Proprietary composite scores (Oura Readiness, Whoop Recovery) explained — including how algorithms weight each input.
View metric →Five population-benchmarked calculators. Enter your data, get your percentile against normative reference values from published research.
Age- and sex-adjusted percentile based on Shaffer & Ginsberg 2017 and Altini normative data.
Open calculator →Enter time in bed and actual sleep time. Get your efficiency percentage and clinical category.
Open calculator →ACSM normative table lookup. Poor / Fair / Good / Excellent / Superior classification by age and sex.
Open calculator →Compare your resting heart rate against AHA population norms.
Open calculator →Composite estimate from sleep efficiency, resting heart rate, VO₂ max, and activity level. Educational use only.
Open calculator →Percentile tables from peer-reviewed literature. Age and sex stratified. No paywalls, no email required.
Normative RMSSD values across age groups 18–70+.
View table →ACSM classifications from poor to superior by decade.
View table →AHA normal ranges, athlete ranges, age stratified.
View table →PSG-measured population data by decade.
View table →N3 slow-wave percentages across the lifespan.
View table →Normal REM proportion across age groups.
View table →Algorithm explanations, score interpretations, and known measurement limitations — for the five most common wearables.
Readiness Score, Sleep Score, and Activity Score — what inputs they use and how they're weighted.
Read guide →How HRV, stress, sleep quality, and activity combine into the 0–100 Body Battery score.
Read guide →Green / Yellow / Red recovery explained. HRV, resting HR, sleep performance, and respiratory rate inputs.
Read guide →Health app metrics including HRV (SDNN), VO₂ max estimation, sleep stages, and AFib detection.
Read guide →Fitbit-powered metrics — Active Zone Minutes, sleep score, and daily readiness explained.
Read guide →