HRV normal range by age: What a good score is and how to improve it

A single HRV reading says little, because HRV swings a lot from day to day and depends on how it was measured. The trend over weeks is what counts.

Your heart does not beat like a metronome. Between two beats there are sometimes 890, sometimes 940, sometimes 910 milliseconds, and that fluctuation is heart rate variability, HRV for short. It arises because your autonomic nervous system keeps adjusting the heart: the vagus nerve brakes, the sympathetic system accelerates.^[5] The finer this back-and-forth, the larger the fluctuation. That is why a high resting HRV is read as a sign of a well-recovered system and a low one as a sign of load, whether from stress, infection, alcohol or yesterday's hard session.

Three metrics keep coming up, and they do not measure the same thing:

• RMSSD: the short-term beat-to-beat fluctuation, in milliseconds. It mostly reflects the vagus and is the number Oura, Whoop and Garmin display as HRV.
• SDNN: the overall spread of all beat intervals in the recording window. It grows with recording length, so a 24-hour SDNN is generally larger than a 5-minute SDNN, because it also captures the slower swings across the day. The Apple Watch shows SDNN.
• pNN50: the share of consecutive beats that differ by more than 50 ms. Crude, but easy to picture.

Because the metrics capture different things, the way a value was recorded matters as much as the value itself. In 1996 a joint Task Force of the European and North American cardiology societies set the measurement standards. Its central point still holds: 5-minute short-term values and 24-hour long-term values cannot be compared, and every value needs its conditions stated (lying or sitting, time of day, breathing).^[5]

Even under identical conditions, HRV swings strongly from day to day, in healthy people just as in professional athletes. Sports scientists who monitor endurance athletes therefore advise against judging a single reading and compare rolling weekly averages with the personal trend instead.^[11] That makes any population chart, including the ones below, a frame for your number rather than a verdict on it.

For Germany, the reference chart comes from the KORA S4 study, which measured the HRV of 1,906 healthy adults aged 25 to 74 in the Augsburg region.^[1] Anyone with heart disease, diabetes, high blood pressure or relevant medication was excluded. Everyone else had 5 minutes of ECG lying down after 5 to 10 minutes of rest, the classic lab value.^[1] The values below are rounded means; the study reports pNN50 as a fraction (for example 0.23), so here it is given in percent.

Source: Voss et al. 2015, 5-minute ECG lying down, 782 women and 1,124 men.^[1]

Three things stand out in that chart. First, RMSSD falls to about half between the mid-20s and the mid-60s and flattens after that. Second, the spread is enormous: in women aged 25 to 34, RMSSD was 42.9 ms give or take 22.8 ms, so the standard deviation is about half the mean. A value of 25 ms is entirely normal in that group, and so is 65 ms. Third, within each age group women and men did not differ meaningfully in RMSSD, SDNN or pNN50.^[1] The separate columns mainly show you how small the sex difference is.

Those Augsburg means fit the international picture. A 2010 systematic review pooled 44 studies of healthy adults.^[2] Across short-term recordings it found a mean RMSSD of about 42 ms and a mean SDNN of about 50 ms, both lower than the 1996 Task Force norms.^[2] The Augsburg means sit in the same range, a little lower, which fits a sample that runs up to age 74.

A mean only marks the middle, though, and most people want to know where their own number falls. A Dutch study of 84,772 healthy people aged 13 to 91 from the Lifelines cohort reports percentiles for exactly that.^[12] It used 10-second resting ECGs, a much shorter window, and its medians land close to the Augsburg means while the spread is wider. Read the range like this: 96 out of 100 healthy people your age sat between the two numbers.

Source: Tegegne et al. 2020, Lifelines cohort, RMSSD from a 10-second resting ECG. The study excluded anyone with heart disease, high blood pressure, type 2 diabetes or obesity, and anyone taking antidepressants, beta blockers or other drugs that act on the vagus.^[12]

Two things in the Dutch data differ from Augsburg. Women aged 20 to 45 had a median about 5 ms higher than men, a small but statistically significant gap. It shrank after 45 and was gone after 60.^[12] And the lower limit barely moves with age: from 20 on, the 2nd percentile stays between about 4 and 12 ms.^[12]

All of these charts come from short recordings, and 24-hour ECGs work on a different scale. In 24-hour ECGs of 260 healthy people aged 10 to 99, the age-group means of SDNN ranged from about 120 to 155 ms between 20 and 79, and were 106 ms at 80 to 99.^[3] That is far above the 5-minute chart, because SDNN grows with recording length.^[5] RMSSD over 24 hours, by contrast, was in a similar range to the 5-minute values, for example 22 ms at ages 60 to 69.^[3] The two methods still do not belong in the same chart, which matters the moment a website hands you a single cutoff for a good score.

A good HRV score is one that stays within your own usual range, measured with the same device under the same conditions. Higher is not always better: in endurance athletes, both falls and rises in HRV have gone along with poor adaptation to training.^[11] Garmin, for one, links an unusually high value against your own baseline to overreaching.^[18] The charts above show where people your age land in the lab, but they cannot tell you whether you are healthy, and a wearable value is recorded under different conditions anyway.

Still, many people want concrete numbers, so here is how to read the common ones, separated by measurement type.

HRV of 20. As a 5-minute lab value that is about average from 55 on.^[1] and roughly the median at 60 to 64 in the Dutch data^[12] In a 30-year-old it is below the median but still above the lowest 2 percent, who sit around 10 to 12 ms.^[12] Low, then, rather than alarming.

HRV of 30. As a 5-minute RMSSD lying down, 30 ms is about average at 35 to 44 and above average from 45 on.^[1] At 25 to 34 it is below average, but within one standard deviation.^[1] A night-time wearable 30 is measured differently and cannot be read off this chart, and in both cases the number alone is not a finding.

HRV of 40. That is about the lab mean at 25 to 34 and above the mean from 35 on.^[1] In the Dutch data it is close to the median for women aged 35 to 39 and men aged 30 to 34.^[12] From 40 on, it is above the median for everyone.^[12] A night-time wearable 40 does not belong in this comparison; judge it against your own baseline.

HRV of 50. As a 5-minute RMSSD, 50 ms is above the mean in every age group.^[1] If your number is an SDNN, 50 ms is about average for 25 to 34.^[1] For a night-time RMSSD from Oura, Whoop or Garmin there is no firm cutoff, because the devices calculate too differently.

HRV of 100. In the 5-minute lab that is rare, more than twice the highest group mean of 43 ms.^[1] Whatever the device, 100 is not a target, and anyone who does not reach it has done nothing wrong.

You will also find thresholds online such as SDNN under 50 ms unhealthy, 50 to 100 ms compromised and over 100 ms healthy. That scale comes from 24-hour risk assessment in cardiac patients, and review papers classify it exactly that way.^[4] It does not fit a 5-minute value or your watch. Mean 5-minute SDNN sits below 50 ms in almost every age group of the chart,^[1] so by that scale most healthy adults would count as unhealthy, which says more about the scale than about them.

What helps more than any threshold is the trend. Compare your value with the rolling 7-day mean, as is standard in training monitoring.^[11] A 7-day average that stays clearly below your usual range for several days is a signal, while a single low morning is not, least of all after stress, alcohol or an infection.^{[9, 10]} That comparison only works, though, when every reading comes from the same device measured the same way.

A night-time value from a ring or watch is not the same kind of number as the lab chart. Wearables measure at night, over hours, from the pulse signal at the wrist or finger, while the chart was recorded during the day, for 5 minutes, by ECG. HRV also follows a daily rhythm and is highest in the early morning hours.^[13] Night values from a wearable therefore often come out somewhat higher than a 5-minute daytime lab value. On top of that, every manufacturer calculates differently. This is how the manufacturers describe it (as of October 2026):

• Oura shows your average night-time RMSSD in milliseconds. That value is the mean of all 5-minute samples taken while you sleep.^[19]
• Whoop also shows a night value. According to Whoop's data science lead, it is a weighted average of overlapping 5-minute windows across the whole sleep, with wake periods removed and likely deep-sleep windows weighted more heavily; the older "deep sleep only" description is out of date.^[20]
• Garmin calls it HRV Status, an average from 5-minute windows across the entire sleep period, shown as a night value and as a 7-day mean.^[18] Garmin needs about three weeks of nightly wear to set your personal baseline range, and the labels Balanced, Unbalanced and Low compare your 7-day average with that baseline, not with a population chart.^[18] Only Poor uses an age reference: it appears when your baseline itself falls below age-based standards.^[18]
• Apple Watch has long stored HRV as SDNN, the metric Apple's Health framework uses,^[27] so even the metric differs from a night-time RMSSD. Series 12 and Ultra 4 add Recovery HRV; according to Apple, Series 12 measures HRV as often as every five minutes, and HRV now appears in the overnight and the new daytime Vitals, though Apple does not say whether the new value is SDNN or RMSSD.^{[21, 22]}
• Chest strap plus app (Polar H10 with HRV4Training, Elite HRV or Kubios) gives a short morning reading lying or sitting, usually 1 to 5 minutes. That comes closest to the lab method.

How close these devices get to an ECG was tested in a small 2021 validation study of 5 young adults, measured sitting and awake rather than overnight.^[6] Against a multi-lead ECG, Oura's RMSSD was off by 6.8 percent on average and HRV4Training with a chest strap by 4.1 percent.^[6] Camera apps varied widely: one, CameraHRV, missed by 112 percent, while two others using the phone camera stayed under 10 percent.^[6] For a ring or a strap that is close enough to follow your own trend; a camera app is only as good as that particular app.

Is there a reference for wearable values? The largest comes from Fitbit, whose researchers analysed one randomly chosen 24-hour period of heartbeat data from 8,203,261 users.^[13] They published tables by age and sex for two hours of the day: 6 to 7 in the morning, near the end of the night, and 6 to 7 in the evening.^[13] The early-morning table is the closest thing to a night reference, but it is not an all-night average like Oura's or Garmin's.

Within those limits, the Fitbit pattern matches the lab: RMSSD falls with age, and women and men barely differ on it.^[13] People who walked more steps per day had higher HRV, in a dose-dependent way, though the authors say trials are needed to show cause and effect.^[13] Fitbit funded the study and other devices calculate differently, so treat these tables as a rough frame, not a verdict on your Oura or Garmin number.

Which device suits which purpose is covered in the HRV wearable comparison, and for reading any of them three simple rules follow. First, never compare values from two devices with each other. Second, compare night-time wearable values only with your own history, never with the lab chart, which is how Garmin and Oura say their numbers are meant to be read.^{[18, 19]} Third, for a value you can hold against studies, measure lying down for 5 minutes, always the same way,^{[1, 5]} which in practice means a chest strap in the morning.

Slow breathing, regular endurance training and less alcohol have the best evidence behind them for moving HRV, though the effects are smaller than wearable marketing suggests. The measures below are sorted by the strength of their evidence.

Slow breathing, around 6 breaths per minute. Slow breathing has the largest pile of studies behind it. A 2022 meta-analysis of 223 studies on voluntarily slowed breathing looked at three time windows: during the breathing, right after a session, and after multi-week programmes.^[7] The part of HRV driven by the vagus rose in all three.^[7] A simple way in: about 6 breaths a minute, for example 5 seconds in and 5 seconds out, for a few minutes a day. It costs nothing, and the authors expect few adverse effects.^[7] Breathe gently rather than forcing deep breaths, and stop if you feel light-headed.

Endurance training. Training works more slowly than breathing, but it shifts the resting value itself. A 2005 meta-analysis pooled training studies and found that the high-frequency part of HRV (the vagal share) rose with an effect size of 0.48.^[8] Effect size is a standard yardstick for how big a change is, and around 0.5 counts as medium. The resting beat interval rose as well, which means a slower resting pulse, though in older people that drop tended to be smaller (a borderline result).^[8] A 2024 meta-analysis of 16 small randomised trials in healthy adults also found that training raised RMSSD, the number Oura, Whoop and Garmin display.^[23] These effects build over weeks to months, so regular base training looks like a better bet than intensity at any price. The Zone 2 and VO2max guide shows what that looks like, and the VO2max calculator estimates your starting point.

Less alcohol. A Finnish observational study followed 4,098 employees and compared each person's nights after self-reported drinking with their own alcohol-free nights.^[9] It tracked an HRV-based recovery score in the first three hours of sleep, and the more people drank, the lower that score was:

• low dose (up to 0.25 g of alcohol per kg of body weight, a bit under half a litre of beer at 75 kg): 9.3 percentage points lower
• moderate dose (0.25 to 0.75 g/kg): 24.0 percentage points lower
• high dose (over 0.75 g/kg): 39.2 percentage points lower

The link was similar in women and men and in active and inactive people, and stronger in younger people.^[9] Since it showed up in the same night's reading, alcohol is probably the quickest of these levers to test against your own trend.

Sleep and regularity. In controlled trials, sleep deprivation lowered RMSSD, a sign of less vagal activity, according to a 2025 meta-analysis of 11 small studies.^[24] For late or irregular sleep there are no comparable pooled numbers, and the sleep guide covers what is proven for sleep duration and quality.

Stress and weight. A 2018 review of 37 studies found that HRV changed under stress in most of them, most often as lower vagal (parasympathetic) activity.^[10] For long-term stress and for weight loss we found no pooled effect on HRV that we could quote here.

What you can skip. For supplements, cold plunges or red light there are no solid data showing a lasting rise in resting HRV. The best-studied supplement, fish oil, produced no statistically significant change in RMSSD in a meta-analysis of short trials and raised only one vagal marker from the frequency analysis slightly.^[25] Cold-water immersion after exercise speeds up vagal recovery in athletes in the short term,^[26] which is a different thing from a higher baseline.

Whether you need a doctor depends on your symptoms, not on your HRV number, and some symptoms cannot wait for an appointment at all. Emergency first: chest pain or pressure, severe shortness of breath, fainting, or palpitations that do not stop or come with chest pain, breathlessness or feeling faint need immediate help. Call 112, and do not wait for a GP appointment.^{[16, 17]} For palpitations that keep coming back but leave you feeling well, see your GP; that is where the ECG or long-term ECG comes in.

Without such symptoms, a low HRV is not a diagnosis. HRV is not a diagnostic value, and no number in the charts marks the line between healthy and sick. The Augsburg chart comes from people who were screened as healthy beforehand, and even so some of them sat far below the mean.^[1] In 24-hour recordings, 25 percent of healthy people over 65 were below published risk thresholds for the SDNN index, and 12 percent for RMSSD.^[3] Thresholds from patient studies do not fit healthy people.

What usually sits behind a low value is something ordinary: an incoming infection, alcohol the evening before,^[9] too little sleep,^[24] a hard training session or acute stress.^[10] Travel across time zones, heat and a late large meal are common everyday causes too. In women HRV also varies across the cycle, usually a little lower in the second half.^[15] All of this is expected and passes.

Medication matters too. The reference studies excluded people taking beta blockers, antidepressants or other drugs that act on the vagus,^{[1, 12]} so the charts do not apply if you take them. Compare yourself with your own baseline, and do not stop or change a medicine because of an HRV number.

Measurement errors can also move the number. Extra beats (extrasystoles) and other artefacts distort HRV. An extra beat from the lower heart chambers, for example, usually shows up as an unusually short interval followed by an unusually long pause.^[14] Even a small share of uncorrected beats changes RMSSD noticeably.^[14] A sudden very high value is therefore no more a success than a low one is an alarm. With atrial fibrillation, HRV analysis can become impossible.^[14]

Outside an emergency, symptoms decide as well. See your GP or cardiologist promptly for:

• palpitations, a racing heart or an irregular pulse that you feel yourself or that the watch flags as possible atrial fibrillation
• dizziness, chest discomfort or shortness of breath that keeps coming back, especially on exertion (sudden or severe symptoms are the emergency above)
• a resting heart rate that stays clearly higher than usual for weeks without an obvious reason
• an HRV drop over two to three weeks together with exhaustion, sleep problems or weight loss

In these cases an ECG or long-term ECG is the right step, because of the symptoms rather than the number. The HRV trend from your watch can still be a useful conversation starter. Without symptoms, a low value is mainly a prompt to look at sleep, alcohol and training load. If you stay below your baseline for longer without finding a reason, a check-up is a sensible choice, not an obligation.