HRV Stress & Recovery Indicator
Compare a baseline and current heart-rate-variability (HRV) reading to gauge recovery versus stress, with an illustrative score and plain-English interpretation. Runs in your browser.
HRV rose meaningfully — parasympathetic (rest-and-digest) activity is up.
Important: this is an illustrative indicator based on the percentage change between two HRV readings, not a clinically validated recovery score. HRV (commonly rMSSD) reflects autonomic balance — higher generally indicates more parasympathetic "recovery" activity (Shaffer & Ginsberg, 2017, Front. Public Health) — but it is highly individual and noisy. Compare against your own multi-day baseline, measured under consistent conditions. Not medical advice.
About this tool
Heart-rate variability (HRV) — the variation in time between heartbeats — is a popular proxy for autonomic nervous-system balance and recovery. Higher HRV generally reflects more parasympathetic ('rest-and-digest') activity and better recovery, while a drop relative to your norm can signal accumulated fatigue, stress, poor sleep, or illness. This tool compares a baseline HRV reading with a current one and reports the percentage change, a simple band (well recovered, stable, or under-recovered), and an illustrative 0–100 indicator. A crucial caveat, stated plainly: there is no single universally validated formula that converts two HRV readings into a recovery 'score' — commercial platforms use proprietary, multi-day, individually-calibrated models. This is an educational indicator based on the change between two readings, useful for understanding the direction of the trend, not a clinical measurement. HRV is highly individual and noisy, so it is only meaningful against your own baseline measured under consistent conditions (same time of day, posture, and device). It is informational, not medical advice. Everything runs in your browser.
How to use it
- Enter your baseline HRV — ideally a multi-day average, in milliseconds (rMSSD).
- Enter today's reading, measured the same way.
- Read the percentage change, band, and illustrative indicator.
- Watch the trend over time rather than reacting to any single reading.
Frequently asked questions
- What is HRV and what does higher mean?
- Heart-rate variability is the fluctuation in intervals between heartbeats. Higher HRV generally indicates greater parasympathetic (recovery) activity and is associated with better recovery and fitness; a relative drop can indicate stress, fatigue, or illness. The common metric is rMSSD, in milliseconds.
- Is the recovery score clinically validated?
- No. This is an illustrative indicator based purely on the percentage change between the two readings you enter. Validated recovery models (used by Whoop, Oura, Garmin, etc.) are proprietary and rely on multi-day, individually calibrated baselines plus other inputs. Treat this as educational.
- Why does HRV need to be compared to my own baseline?
- Absolute HRV varies enormously between people due to age, genetics, and fitness, so one person's "high" is another's "low". Only the trend relative to your own consistent baseline is meaningful — which is why this tool works on change, not absolute value.
- How should I measure HRV consistently?
- Same time of day (typically on waking), same posture (lying or seated), same device, before caffeine or exercise. Inconsistent conditions add noise that can swamp the real signal.
- What should I do if my HRV drops a lot?
- A single low reading is often just noise. A sustained drop across several days alongside fatigue, poor sleep, or soreness may suggest backing off training intensity and prioritizing recovery. Persistent changes or symptoms warrant medical advice.
- Is this medical advice?
- No. It is an informational, educational indicator. HRV is not a diagnostic tool here; consult a healthcare professional for concerns about stress, heart health, or overtraining.