HRV Score Interpreter
Paste your morning RMSSD reading from any wearable and instantly get a 0-100 readiness score, a percentile compared to people your age, and a plain-English verdict on whether to train hard or rest. Nothing uploaded.
HRV Score
0-100 scale - 70+ is high, 50-69 moderate, below 50 low
Age-Normed Comparison
7-Day Rolling Trend
What affects your HRV?
- Sleep quality: Poor or short sleep suppresses the nervous system overnight and lowers the next morning's HRV significantly.
- Alcohol: Even one or two drinks can drop RMSSD by 10-20 ms the following morning as the body metabolises alcohol.
- Overtraining: A string of hard sessions without rest accumulates fatigue; HRV will trend down over days or weeks.
- Illness: Infection activates the immune system and raises sympathetic tone, often causing a sudden HRV dip before symptoms appear.
- Stress: Psychological stress raises cortisol and shifts balance toward the fight-or-flight branch, reducing HRV.
- Breathing and hydration: Slow diaphragmatic breathing and good hydration both support higher HRV readings.
Learn more: reading your HRV numbers
How the score is worked out
The calculator takes your RMSSD, the root mean square of the differences between successive heartbeats in milliseconds, and turns it into a 0 to 100 score using score = ln(RMSSD) / 6.5 x 100, rounded and kept between 1 and 100. An RMSSD of 25 ms scores 50, 48 ms scores 60 and 100 ms scores 71. The log scale squeezes a wide range of raw values into a narrow score band.
The percentile compares your reading with a built-in average for your age group and sex, assuming a standard deviation of 12 ms. For a man aged 26 to 35 the average is 48 ms, so 48 ms is the 50th percentile and 60 ms is about the 84th. The age averages are approximate figures from the calculator's own table, and published norms differ.
There is no universal good number
TrainingPeaks' explainer on HRV numbers and age says average HRV levels vary by a factor of 10 to 1 or more depending on the group being compared, and that HRV declines from around 80 ms in teenagers to 25 ms over age 75. Because people differ so much, your own baseline tells you more than any chart.
Trends over single readings
The same article says changes of 10% in either direction are not unusual from one day to the next, and that a seven-day rolling average reveals the underlying trend. The calculator's trend check compares the average of your earlier readings with your recent ones and calls a change improving or declining only when it passes 2 ms.
The readiness labels, which switch at scores of 50 and 70, are the calculator's own cutoffs for planning training, not clinical categories. This tool does not diagnose anything. If you are worried about your heart rate or how you feel, talk to a doctor.
FAQ
What counts as a good RMSSD?
There is no single number. Log your own readings for a few weeks and compare new ones with that personal average, not with a chart for other people.
Why does my number move so much day to day?
TrainingPeaks says changes of 10% either way are not unusual. Sleep, stress, alcohol and training all move HRV, so a single reading is noisy.
Should I use this to diagnose a health problem?
No. It is for tracking your own training data. Speak to a doctor about any health concern instead of relying on a score.