HRV by age chart and checker

What is HRV?

Heart rate variability (HRV) is how much the time between your heartbeats changes from one beat to the next, measured in milliseconds (ms). It is used as a sign of how active the “rest and digest” side of your nervous system is, the part that slows your heart through the vagus nerve.

Your heart does not beat like a metronome. At 60 beats a minute, the gaps between beats are not all exactly one second: they might be 0.95, then 1.04, then 0.98 seconds. The gaps get a little shorter as you breathe in and longer as you breathe out.

RMSSD is the number most rings and bands show. It is the typical size of the change from one gap to the next. Shaffer and Ginsberg describe it as the main time-based measure of the vagus nerve’s effect on the heart. Apple Health shows SDNN instead, the overall spread of the gaps. The two give different numbers, so they cannot be swapped (RMSSD vs SDNN).

Higher is usually better when you compare you with yourself. HRV tends to go down after alcohol, poor sleep, illness, stress and hard training, and back up as you recover. A very high reading is not always good news: an irregular heart rhythm such as atrial fibrillation can also push HRV up.

Comparing with other people tells you much less. HRV varies a lot between healthy people of the same age, and devices measure it in different ways. Oura advises comparing your HRV only with your own past readings, not with other people’s.

What is a good HRV score?

There is no single good HRV score. For you, a good score is one at or above your own usual range. HRV is also lower at older ages: in a study of 1,906 healthy adults, the median RMSSD was 38.4 ms for women and 36.2 ms for men aged 25 to 34, and 16.9 and 16.7 ms at 65 to 74.

This table shows the median for each age group: half of the group had a higher reading and half a lower one. The numbers come from 5-minute ECG recordings taken lying down at rest (Voss and colleagues, 2015). A watch or ring reading taken while you sleep is measured differently, so use the table as a rough guide.

A wide range around each median is normal. The HRV by age chart below shows the middle half of each group, and the checker places your own number on it.

What moves your HRV

• Sleep. After a night without sleep, the “rest and digest” part of HRV went down in a lab study of 18 healthy adults.
• Alcohol. In 4,098 Finnish employees, HRV in the first 3 hours of sleep was lower on nights after drinking, and lower still the more they drank. Small amounts had an effect too.
• Illness. In 2,745 Fitbit users with COVID-19, night-time RMSSD fell around the day symptoms started, sometimes a few days before.
• Stress. A review of 37 studies found that psychological stress most often lowered the “rest and digest” part of HRV.
• Training. After exercise, this part of HRV took up to 24 hours to recover after easy sessions and at least 48 hours after hard ones. Fitter people recovered faster.

HRV with POTS, ME/CFS or long COVID

On average, studies find lower HRV in groups of people with these conditions than in healthy people: lower RMSSD in POTS (a review of 20 studies), lower resting “rest and digest” HRV in ME/CFS (a review of 64 studies), and lower SDNN after COVID-19, including long COVID (a review of 11 studies, whose authors note the studies had limitations). The study behind the chart left out people with chronic illness, so a reading below the middle half may simply be your normal. Your own baseline is the better comparison.

If your heart races when you stand up, the at-home standing test records your heart rate lying down and standing for your doctor. For using HRV to pace, see HRV and pacing below.

HRV by age chart

These values come from Voss and colleagues (2015), who analysed 5-minute ECG recordings taken lying down after 5 to 10 minutes of rest in 1,906 healthy adults aged 25 to 74 from the KORA S4 population study in Germany. Each bar shows the middle half of the group, from the 25th to the 75th percentile, and the line marks the median: half the group had a higher reading and half a lower one. We use one large study rather than a mix of small ones: a 2010 review of 44 studies found that short-term HRV values differed between studies partly because of how heartbeats were recorded and cleaned, and called for large population studies.

Average HRV by age

The paper also gives the average (mean) and standard deviation for each group. In every group the average is higher than the median, because a few people have much higher readings than the rest.

Medians and percentiles: the paper’s supporting information S1, Tables C (women) and E (men). Averages: Tables 5 (women) and 7 (men). Group sizes: Table 1. The study left out people with heart disease, high blood pressure, diabetes, thyroid disease or cancer, and people taking medicines that affect heart rate, hormone replacement or the contraceptive pill (Table 2). If you live with a chronic illness or take one of these medicines, you are being compared with a group that did not.

RMSSD vs SDNN

Devices show one of two HRV numbers. Shaffer and Ginsberg’s overview of HRV metrics describes them like this:

The same heartbeats give different RMSSD and SDNN numbers, so the two cannot be swapped. That is why the checker uses the study’s SDNN values for Apple Health and its RMSSD values for overnight wearables.

Why HRV changes with age

In the study, RMSSD and SDNN were lower in older age groups, for women and for men. The authors found the strongest effect of age between the 35 to 44 and 45 to 54 groups. Between 55 to 64 and 65 to 74 there was no significant difference. The paper links lower HRV with age to changes in the heart and blood vessels, such as the loss of pacemaker cells in the heart and less elastic arteries.

Within each age decade, RMSSD and SDNN did not differ significantly between women and men (Table 9). Some other HRV measures did differ in younger adults; the authors suggest hormones as a possible reason, and those differences faded after about 55.

Why your watch or ring shows a different number

Different measures. Apple Health stores HRV as SDNN. Android’s Health Connect stores HRV as RMSSD, and Oura, WHOOP, Fitbit and Polar report RMSSD. An Apple Watch number and an Oura number are different measures, so they are not directly comparable.

Different timing. Most rings and bands take their reading while you sleep. Oura averages 5-minute samples across the night, Fitbit uses your main sleep, Polar uses roughly the first four hours of sleep, and Garmin reads your heart rate while you sleep. The study used 5-minute ECG recordings taken lying down after 5 to 10 minutes of rest. Shaffer and Ginsberg note that 24-hour and 5-minute HRV values cannot substitute for each other even though they use the same formulas. So comparing a sleep average or a watch reading with this chart is approximate.

Different sensors. The Oura Ring estimates heartbeats from light shone through the skin (PPG) rather than from an ECG. In one study, its nightly averages agreed with ECG better than single 5-minute readings, and more than half of the older participants had HRV errors above 10%.

The most reliable comparison is with your own readings from the same device, taken the same way. Oura’s guidance is to compare your HRV with your own trend, not with other people’s.

HRV and pacing with a chronic illness

Some people living with ME/CFS, long COVID, POTS and other conditions watch their HRV trend as one signal when they pace. Visible’s free app takes a morning HRV reading with your phone camera, and mypacing compares HRV from Apple Health or Health Connect with your usual range over the last four weeks (see our guide to pacing apps). In Juno, a lower HRV than your normal raises the estimated spoon cost of planned activities; you can try the same idea in the free spoon calculator. For pacing itself, see how to pace to prevent crashes and why you can crash a day after activity.

What these approaches share is a comparison with your own baseline rather than with a chart like the one above. HRV is one signal among many, next to how you feel, your symptoms, sleep and activity. If your readings change and you feel unwell, or you are unsure what they mean for you, talk to a clinician.

Sources

1. 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
2. Voss A et al. 2015, supporting information S1: medians and interquartile ranges (Tables C and E, DOCX)
3. Shaffer F, Ginsberg JP. An overview of heart rate variability metrics and norms. Front Public Health, 2017;5:258
4. Nunan D, Sandercock GR, Brodie DA. A quantitative systematic review of normal values for short-term heart rate variability in healthy adults. Pacing Clin Electrophysiol, 2010;33(11):1407–17
5. Liang T, Yilmaz G, Soon CS. Deriving accurate nocturnal heart rate, rMSSD and frequency HRV from the Oura Ring. Sensors, 2024
6. Apple Developer: heartRateVariabilitySDNN (HealthKit)
7. Android Developers: HeartRateVariabilityRmssdRecord (Health Connect)
8. Oura: Heart rate variability
9. Oura: The HRV of the Ring, comparison of the Oura Ring to ECG (PDF)
10. WHOOP Developer: Recovery
11. Google Health Help: Track your vitals (Fitbit)
12. Fitbit Web API: Get HRV summary by date
13. Polar: Nightly Recharge recovery measurement
14. Garmin fēnix 7 owner’s manual: Heart rate variability status
15. Zhong X et al. Increased sympathetic and decreased parasympathetic cardiovascular modulation in normal humans with acute sleep deprivation. J Appl Physiol, 2005;98(6):2024–32
16. Pietilä J et al. Acute effect of alcohol intake on cardiovascular autonomic regulation during the first hours of sleep in a large real-world sample of Finnish employees. JMIR Ment Health, 2018;5(1):e23
17. Natarajan A, Su HW, Heneghan C. Assessment of physiological signs associated with COVID-19 measured using wearable devices. NPJ Digit Med, 2020;3:156
18. Kim HG et al. Stress and heart rate variability: a meta-analysis and review of the literature. Psychiatry Investig, 2018;15(3):235–45
19. Stanley J, Peake JM, Buchheit M. Cardiac parasympathetic reactivation following exercise: implications for training prescription. Sports Med, 2013;43(12):1259–77
20. Swai J et al. Heart rate and heart rate variability comparison between postural orthostatic tachycardia syndrome versus healthy participants; a systematic review and meta-analysis. BMC Cardiovasc Disord, 2019;19:320
21. Nelson MJ et al. Evidence of altered cardiac autonomic regulation in myalgic encephalomyelitis/chronic fatigue syndrome: a systematic review and meta-analysis. Medicine, 2019;98(43):e17600
22. Suh HW, Kwon CY, Lee B. Long-term impact of COVID-19 on heart rate variability: a systematic review of observational studies. Healthcare, 2023;11(8):1095

Last updated 17 October 2026. This page is general information. It does not diagnose and does not replace advice from your own clinician.