HRV Score Interpretation Guide

Heart rate variability (HRV) measures the variation in time between consecutive heartbeats. A higher HRV generally indicates better recovery, lower stress, and greater autonomic nervous system flexibility. It is one of the more useful metrics from wearables because it reflects both sleep quality and stress load before you consciously feel them.

What RMSSD means

Most wearables (WHOOP, Oura, Apple Watch, Garmin) report HRV as RMSSD: the root mean square of successive differences between heartbeat intervals. This is measured in milliseconds. Higher is generally better, but your personal baseline matters far more than any population average.

That last point is worth taking seriously, and it is why this page asks for your 7-day average as well as today’s reading. If you fill that in, the verdict is built from your own trend and the population comparison drops to a footnote. Leave it blank and you get the population comparison, which is a much blunter instrument.

Age matters significantly. HRV declines with age, roughly 1 to 2 ms of RMSSD per year after the mid-20s. A 40-year-old with an HRV of 50 ms is likely healthier than a 60-year-old with 50 ms, but the 60-year-old may be in excellent shape for their age.

The rough expected RMSSD by age:

Look at how wide those bands are. At 35, anything from 40 to 80 ms is ordinary, which is a factor of two. That spread is the real reason a single reading tells you almost nothing about your health and quite a lot about your last 24 hours.

Day-to-day trends matter more than absolute numbers. A 10 to 15% drop from your 7-day rolling average is a meaningful signal, usually incomplete recovery, elevated stress, illness coming on, or alcohol still in the system from the night before. Alcohol is the big one and it is remarkably consistent: two drinks will visibly dent most people’s HRV, and the reading often catches it before the hangover does.

A consistent HRV 20% above your baseline suggests you are well recovered and ready for hard training.

One caveat about the fitness setting below. Trained endurance athletes do carry higher HRV, so selecting a higher training level raises the number this page expects of you. That can make a perfectly normal reading look disappointing. When your reading sits inside the population band for your age, the page will say so rather than calling it low, because it is not low.