Normal HRV by age
In a study of 1,906 healthy adults (Voss et al., PLOS ONE 2015), average resting HRV fell steadily with age: SDNN from about 49–50 ms at ages 25–34 to about 28–30 ms at 65–74, and RMSSD from about 40–43 ms to about 19 ms. Healthy people spread widely around those averages, so treat them as reference points, not targets. Apple Watch reports HRV as SDNN.
Ranges vary a lot between healthy people, and the way HRV is measured changes the number. The averages below come from 5-minute resting ECGs in one population study. They are not targets or diagnostic thresholds. This page is general information, not medical advice.
HRV by age: SDNN (the measure Apple Watch reports)
Mean ± one standard deviation, in milliseconds, from 5-minute supine resting ECGs (Voss et al., 2015, Tables 5 and 7).
| Age | Women SDNN (ms) | Men SDNN (ms) |
|---|---|---|
| 25–34 | 48.7 ± 19.0 | 50.0 ± 20.9 |
| 35–44 | 45.4 ± 20.5 | 44.6 ± 16.8 |
| 45–54 | 36.9 ± 13.8 | 36.8 ± 14.6 |
| 55–64 | 30.6 ± 12.4 | 32.8 ± 14.7 |
| 65–74 | 27.8 ± 11.8 | 29.6 ± 13.2 |
HRV by age: RMSSD
| Age | Women RMSSD (ms) | Men RMSSD (ms) |
|---|---|---|
| 25–34 | 42.9 ± 22.8 | 39.7 ± 19.9 |
| 35–44 | 35.4 ± 18.5 | 32.0 ± 16.5 |
| 45–54 | 26.3 ± 13.6 | 23.0 ± 10.9 |
| 55–64 | 21.4 ± 11.9 | 19.9 ± 11.1 |
| 65–74 | 19.1 ± 11.8 | 19.1 ± 10.7 |
The study included 782 women and 1,124 men from the population-based KORA S4 cohort in Germany, after excluding people with arrhythmias, documented diseases such as hypertension, diabetes or heart disease, heart-rate-affecting medication, and pregnancy. Group sizes ranged from 62 (women 65–74) to 330 (men 25–34).
How to read your own number
Match the measure. Apple Watch and Apple Health store HRV as SDNN. Many other wearables report RMSSD. A 45 ms SDNN and a 45 ms RMSSD are different things.
Match the conditions. The study numbers were recorded lying down after several minutes of rest, over five minutes, with an ECG. A watch takes short optical readings from the wrist whenever you happen to be still. Your readings will vary more, and the absolute level may not line up with a clinical recording.
Watch the trend, not one reading. HRV moves day to day with sleep, alcohol, stress, illness and training. A single reading below the band says little. A sustained shift from your own baseline over weeks is more informative.
Sources
- Voss A, Schroeder R, Heitmann A, Peters A, Perz S. Short-Term Heart Rate Variability — Influence of Gender and Age in Healthy Subjects. PLOS ONE 2015;10(3):e0118308. Tables 1, 5 and 7.
- Apple Developer Documentation. heartRateVariabilitySDNN — HealthKit records Apple Watch HRV as SDNN.
Body Vitals — your HRV against your own baseline
Body Vitals reads the HRV your Apple Watch already writes to Apple Health and shows it as iPhone widgets, alongside sleep and resting heart rate, in a daily Readiness Score calibrated to your personal 90-day baseline. On-device, no account, no extra hardware.
View on the App StoreFrequently asked questions
What is a normal HRV by age?
In the largest age-and-sex breakdown of short-term resting HRV in healthy adults (Voss et al., PLOS ONE 2015, 1,906 people), average SDNN was about 49-50 ms at ages 25-34, 45 ms at 35-44, 37 ms at 45-54, 31-33 ms at 55-64 and 28-30 ms at 65-74. Average RMSSD went from about 40-43 ms to about 19 ms over the same ages. The standard deviations are large, so many healthy people sit well above or below the average.
Is my Apple Watch HRV comparable to these numbers?
Only roughly. Apple's HealthKit documentation says Apple Watch HRV is SDNN, the same measure as the SDNN column here, but the study used 5-minute ECG recordings taken lying down after 5-10 minutes of rest, while the watch takes short optical readings from the wrist. Use the table as context and compare your readings mainly with your own baseline, measured the same way.
What is the difference between SDNN and RMSSD?
Both are time-domain HRV measures in milliseconds. SDNN is the standard deviation of all normal beat-to-beat intervals in a recording; RMSSD is the root mean square of successive differences between neighbouring beats. Apple Watch reports SDNN; many other wearables report RMSSD. The two are not interchangeable, so compare like with like.
Does HRV really decrease with age?
Yes, on average. In the Voss study both SDNN and RMSSD declined across the age groups in women and in men, with the clearest drop between the 35-44 and 45-54 groups and no significant difference between 55-64 and 65-74. Ranges still vary widely between individuals of the same age.
Do men and women have different HRV?
Less than you might expect. The study authors describe the influence of gender as more marginal than initially expected. Women in the younger groups had slightly higher average RMSSD than men, while average SDNN was similar.
What is a good HRV score?
There is no single good number. A population average describes a group, not you, and HRV is affected by sleep, alcohol, illness, training load and how it is measured. The most useful comparison is your own baseline over weeks. This page is general information, not medical advice.