There is no single normal HRV: in healthy adults, resting HRV is highest in young adulthood and falls steadily with age, and the same number can be typical at 60 and low at 25. Values also depend on the measure ( RMSSD RMSSD Root mean square of successive differences: an HRV metric built from how much each heartbeat interval differs from the next. It mainly reflects vagal activity. More about RMSSD or SDNN SDNN The standard deviation of all NN intervals in a recording, in milliseconds. It measures overall variability, and its value depends strongly on how long the recording lasts. More about SDNN ), the device and when you measure, so compare your number with norms collected the same way, and above all with your own baseline Baseline Your own usual HRV level and range, built from weeks of readings taken the same way. Comparing a reading with your baseline says more than comparing it with other people. More about Baseline .
Normal HRV by age
The tables below come from one of the largest sets of clinical reference values. Voss and colleagues (2015) analysed 5-minute ECG ECG A recording of the heart's electrical activity, taken with electrodes on the skin. ECG-based RR intervals are the reference standard for measuring HRV. More about ECG readings from 1,906 healthy adults aged 25 to 74 in the KORA S4 population study in southern Germany: 782 women and 1,124 men. People lay down and rested for 5 to 10 minutes before the recording.
Each cell shows the median, with the 25th to 75th percentile in brackets. Half of the people in each group fell inside the bracket. A quarter were below it and a quarter above it.
Clinical reference values: RMSSD
| Age | Women, RMSSD (ms) | Men, RMSSD (ms) |
|---|---|---|
| 25–34 | 38.4 (26.1–54.5) | 36.2 (26.2–48.5) |
| 35–44 | 30.5 (22.4–45.7) | 28.7 (20.9–39.0) |
| 45–54 | 23.7 (16.9–31.3) | 21.5 (15.7–29.6) |
| 55–64 | 18.9 (13.2–27.3) | 17.5 (12.5–24.8) |
| 65–74 | 16.9 (11.1–23.9) | 16.7 (11.8–23.4) |
RMSSD by age and sex: median (25th–75th percentile) from 5-minute ECG recordings, lying down after rest, in healthy adults from the KORA S4 study, Germany. Groups ranged from 62 to 330 people. Source: Voss and colleagues, 2015, supporting information.
Clinical reference values: SDNN
| Age | Women, SDNN (ms) | Men, SDNN (ms) |
|---|---|---|
| 25–34 | 44.9 (35.4–58.1) | 46.0 (36.4–58.9) |
| 35–44 | 40.2 (32.9–53.7) | 42.6 (32.3–53.1) |
| 45–54 | 35.5 (26.5–44.5) | 34.5 (26.1–44.3) |
| 55–64 | 29.0 (22.8–35.2) | 29.9 (22.0–39.3) |
| 65–74 | 26.0 (18.7–32.5) | 26.5 (20.1–35.4) |
SDNN by age and sex: median (25th–75th percentile), same people and conditions as the RMSSD table. Source: Voss and colleagues, 2015, supporting information.
Median RMSSD falls by more than half between the late twenties and the late sixties. SDNN falls too, but more slowly.
Average adult values from many studies
Nunan and colleagues (2010) pooled 44 studies of healthy adults published between 1997 and 2008, with 21,438 participants. As reproduced by Shaffer and Ginsberg (2017), the average short-term values were:
- RMSSD: mean 42 ms, SD 15 ms, with study averages ranging from 19 to 75 ms (15 studies)
- SDNN: mean 50 ms, SD 16 ms, with study averages ranging from 32 to 93 ms (27 studies)
The SD here describes how much the study averages differed from each other, not how much individual people differ. The spread between people is much wider. Recording length, body position and breathing also varied between the studies, and the review gives no age breakdown.
What wearable data show
Natarajan and colleagues (2020) analysed optical ( PPG PPG An optical method that shines light into the skin and detects the pulse of blood with each heartbeat. Most watches, rings and phone-camera apps use it to estimate HRV. More about PPG ) heartbeat data from 8,203,261 Fitbit users over one 24-hour period each, using 5-minute windows. HRV fell with age, and the vagal measures fell faster than the others. HRV also changed a lot with the time of day, so the authors gave separate benchmark tables for two times of day. RMSSD did not differ by sex in that data.
These values come from wrist sensors, at set times of day, in people who own a Fitbit. They are not a substitute for clinical norms, and clinical norms are not a perfect match for your overnight ring or watch value either.
Children and older adults
Two studies extend the age range. Van den Berg and colleagues (2018) used 13,943 standard 10-second ECGs from people aged 11 days to 91 years, with HRV corrected for heart rate. The median fell steadily from birth to old age, but the upper limit of normal rose sharply after 60. Umetani and colleagues (1998) used 24-hour recordings in 260 healthy people aged 10 to 99. RMSSD fell fastest: by the sixth decade of life it had reached 47% of the value in the second decade, and then it levelled off.
What is a good HRV for my age?
A good HRV is one that is normal for you. Population tables can tell you where you sit, not whether you are healthy.
Percentiles help here. If your RMSSD is at the 30th percentile for your age, 30% of healthy people in that study had a lower value. That is an ordinary result, not a bad one. Everyone in these tables was healthy, including those in the bottom quarter.
Two examples, using the RMSSD table:
- A 40-year-old woman with an RMSSD of 25 ms sits between the 25th percentile (22.4 ms) and the median (30.5 ms) for her age group. That is well inside the typical range.
- A 60-year-old man with an RMSSD of 30 ms sits above the 75th percentile (24.8 ms) for his age group. That is higher than most men his age in the study.
So use the tables as a rough guide. If your number is in or near the bracket for your age, you are in typical territory. If it is far outside, first check that you are comparing like with like (see below). For a fuller answer, read what is a good HRV?
Normal HRV for women and men
The differences are small and depend on the measure. A meta-analysis of 63,612 people found that women, on average, had a slightly lower SDNN but more high-frequency power HF power The share of heart rate variability in fast rhythms of 0.15 to 0.40 Hz, the range of normal breathing. It mainly reflects vagal activity when breathing is 9 to 24 breaths a minute. More about HF power , a vagal measure, than men (Koenig and Thayer, 2016). The Voss tables show the same pattern: younger women had a slightly higher median RMSSD and a slightly lower SDNN than men of the same age.
Age matters here too. In the 24-hour study, gaps between the sexes shrank after 30 and disappeared after 50 (Umetani and colleagues, 1998). In a large app-based study, HRV was not associated with sex at all (Altini and Plews, 2021).
For many women, HRV also shifts a little across the menstrual cycle. See HRV and the menstrual cycle.
Why HRV charts disagree
Search for “HRV chart by age” and you will find tables that do not match. Usually each one measured something different.
| Factor | Why it changes the number | Example |
|---|---|---|
| Measure | RMSSD and SDNN capture different parts of the variation | Apple Watch reports SDNN; most rings report RMSSD |
| Body position | Posture and breathing change the balance of the nervous system during a reading | The Voss norms were taken lying down after rest |
| Recording length | SDNN grows with longer recordings | A 24-hour SDNN is not comparable with a 5-minute one |
| Time of day | HRV changes a lot through the day and night | The Fitbit study needed separate tables for two times of day |
| Device and software | Each maker filters beats and picks its window differently | Two wearables worn on the same night disagree |
| Population | Age, health and fitness of the people studied | Athletes, office workers or patients |
| Statistic | A mean is pulled up by a few very high values; a median is not | Nunan’s 42 ms is an average of study means; Voss gives medians |
The lesson on RMSSD, SDNN and lnRMSSD explains why the measure alone can double or halve a number.
Fitness, genetics and other reasons people differ
Even among healthy people of the same age and sex, HRV varies a lot. In the Voss data, the top quarter of women aged 25 to 34 had an RMSSD above 54.5 ms, while the bottom quarter were below 26.1 ms.
Some of that is fitness. In a sample of 28,175 people, HRV fell with age and was weakly linked with being more physically active (Altini and Plews, 2021). Some of it comes from genes and body build, and some from how and when the reading was taken. The lesson on comparing your HRV to norms covers how to account for this.
How to compare your own number fairly
Before you compare yourself with any table, check four things:
- Same measure. Compare RMSSD with RMSSD and SDNN with SDNN.
- Similar conditions. The clinical tables above used 5-minute readings lying down after rest. An overnight average is a different kind of number.
- Same kind of device. An ECG chest strap is closer to clinical conditions than a ring or watch.
- Your age and sex. Use the row that matches you.
Then stop comparing yourself with other people and start comparing yourself with yourself. Your baseline, built from a few weeks of readings taken the same way, shows what is normal for your body. A drop from your own baseline means far more than sitting at the 40th percentile of a German study.
Look at the sizes involved. In a large app-based study, people’s morning HRV fell by about 12% after heavy drinking and about 10% when they were sick, compared with their own usual values (Altini and Plews, 2021). For someone whose usual RMSSD is 40 ms, that is a drop of 4 to 5 ms. In the Voss table, the middle half of people aged 25 to 34 spans more than 20 ms. A change that size disappears inside a population range, but it stands out clearly against your own baseline. The lesson on building your HRV baseline shows how.
When a low or high number is worth attention
This page compares you with population data. It cannot tell you whether you are healthy.
A low HRV on its own is common and usually harmless, especially after poor sleep, alcohol or a hard workout. It is more worth noticing when it stays well below your own baseline for weeks. A sudden, unexplained jump can also be a sign of measurement errors or extra heartbeats. Read what a low HRV means and why your HRV is suddenly high.
Talk to a doctor if you have palpitations, fainting, chest pain or breathlessness, whatever your HRV number is.