What is a good HRV? Ranges and what your number means

A good HRV is one that sits at or above your own recent baseline. For context, a 5-minute resting RMSSD in healthy adults averages about 42 ms, with study averages from 19 to 75 ms (Nunan et al., 2010). Your age, the metric your device uses and when you measure change the number so much that your own 7-day trend tells you more than any population figure.

This guide explains what heart rate variability is, the published ranges, why devices disagree, what moves your number up or down, and how to read it day to day.

What is heart rate variability?

Heart rate variability (HRV) is the variation in time between consecutive heartbeats, measured in milliseconds. A heart at 60 beats per minute does not beat exactly once per second. The gaps vary, for example 0.95 s, then 1.05 s. HRV quantifies that variation. At rest, larger variation generally reflects stronger parasympathetic (vagal) activity.

The autonomic nervous system sets the timing of each beat. The parasympathetic branch, mostly through the vagus nerve, slows the heart and adds beat-to-beat variation. The sympathetic branch speeds the heart up and tends to make the rhythm more even. Shaffer and Ginsberg (2017) describe RMSSD as "the primary time-domain measure used to estimate the vagally mediated changes reflected in HRV."

HRV is therefore a window into how your body balances stress and recovery. It is not a measure of heart health on its own, and a single reading says little. Trends over days and weeks carry the useful information.

Which HRV numbers do devices report?

Consumer devices mostly report one of two time-domain metrics: RMSSD or SDNN. RMSSD (root mean square of successive differences) tracks short-term, beat-to-beat change and mainly reflects vagal activity. SDNN (standard deviation of normal-to-normal intervals) captures all variation in the window. The two give different values for the same heart.

Metric	What it measures	Main influence	Who reports it
RMSSD	Beat-to-beat differences between normal heartbeats	Parasympathetic (vagal) activity	Many wearables and phone camera apps
SDNN	Standard deviation of all normal beat intervals in the window	Both autonomic branches, plus slower rhythms	Apple Health (HealthKit stores Apple Watch HRV as SDNN; iOS 27 adds an RMSSD type)
ln RMSSD	Natural log of RMSSD, often rescaled to a score	Same as RMSSD	Some training apps

Source: Shaffer and Ginsberg, 2017; Apple HealthKit documentation.

Apple's HealthKit documentation states that it "uses SDNN heart rate variability." iOS 27 adds a separate RMSSD data type, so check which one an app reads. Many other wearables and apps report RMSSD. Because the formulas differ, an SDNN of 45 ms and an RMSSD of 45 ms are not the same physiological state. For a full comparison, read our explainer on RMSSD vs SDNN.

What is a normal HRV range for adults?

A normal short-term resting HRV for healthy adults is roughly 19 to 75 ms RMSSD, with an average near 42 ms, based on a systematic review of 44 studies and 21,438 participants (Nunan et al., 2010). The same review put 5-minute SDNN at about 50 ms, with study averages from 32 to 93 ms.

The table below collects published reference values. Use the row that matches how your number was recorded. Shaffer and Ginsberg warn that 24-hour, short-term and ultra-short values "are not interchangeable."

Recording type	Metric	Published value	Source
5 min, resting, lab ECG	RMSSD	Mean 42 ms (SD 15), study means 19 to 75 ms	Nunan et al., 2010
5 min, resting, lab ECG	SDNN	Mean 50 ms (SD 16), study means 32 to 93 ms	Nunan et al., 2010
24 h, Holter ECG	SDNN	Below 50 ms classed unhealthy, 50 to 100 ms compromised, above 100 ms healthy	Cited in Shaffer and Ginsberg, 2017
Morning, phone app, 28,175 users	RMSSD	69 ms on average (SD 37)	Altini and Plews, 2021
Overnight, smart ring	Not stated	Typical values from under 20 to over 200 ms	Oura Help

Two points stand out. First, the app-user average is higher than the lab average. The groups, sensors and time of day differ, so the two numbers are not directly comparable. Second, the spread is wide. A value of 25 ms and a value of 90 ms can both be normal for different healthy people.

What is a good HRV for my age?

HRV declines with age. In a German population study of 1,906 healthy adults, average 5-minute RMSSD fell from about 40 to 43 ms at ages 25 to 34 to about 19 ms at ages 65 to 74 (Voss et al., 2015). A "good" number for a 60-year-old is lower than for a 25-year-old, so compare with your age group.

Age has a stronger effect than sex on most HRV metrics. Voss et al. concluded that sex effects on time-domain indices were small compared with age effects. In a large app dataset, Altini and Plews (2021) found population HRV reduced with age (r = -0.35), and found no meaningful difference between men and women in morning RMSSD.

The full decade-by-decade table, with values for men and women, is in our HRV chart by age and sex. For women, cycle phase also shifts HRV. See good HRV for women and the menstrual cycle.

Is higher HRV always better?

Higher resting HRV is generally associated with better aerobic fitness, better recovery and lower cardiovascular risk at the population level. But higher is not always better for an individual. Irregular heart rhythms, such as frequent ectopic beats, can inflate HRV values, so a sudden large jump is not automatically a good sign.

Shaffer and Ginsberg state it directly: "Higher HRV is not always better since pathological conditions can produce HRV." This is why HRV formulas are meant to use only normal beats, with ectopic beats removed first. A device that cannot remove them may report a high value that reflects rhythm noise, not recovery.

At the population level, low HRV carries weight. A meta-analysis of 8 studies with 21,988 participants without known heart disease found that low HRV was associated with a 32% to 45% higher risk of a first cardiovascular event (Hillebrand et al., 2013). For SDNN, the lowest group had a pooled relative risk of 1.35 compared with the highest group. That is an association in groups. It does not mean a low reading predicts anything for one person on one day.

If your HRV changes sharply and you also have symptoms such as palpitations, chest pain, shortness of breath or fainting, see a doctor. A wellness app or wearable cannot assess heart rhythm problems.

Why is your own baseline more useful than population averages?

Your baseline is the typical range of your own HRV over recent weeks, measured the same way each time. It is more useful than population averages because healthy people differ by a factor of two or three, while your own day-to-day changes show how you respond to training, sleep, alcohol and illness.

HRV is noisy from one day to the next. Altini and Plews (2021) cite a typical error of about 12% for rMSSD in daily measurements and a smallest worthwhile change of about 3%. A single morning that is 10% lower can be ordinary noise. A 7-day average that drifts 10% below your baseline is a clearer signal.

Researchers who monitor elite athletes recommend the same approach. Plews et al. (2013) list "the use of appropriate averaging techniques" as a solution to day-to-day noise, and show that longitudinal monitoring is needed to understand an athlete's "individual HRV fingerprint."

A practical way to read your number:

• Above baseline: often seen after rest days and good sleep. Fine for normal training.
• Within baseline: the usual state. No change needed.
• Below baseline for 1 day: common after a hard session, a late meal or a drink. Usually not a concern.
• Below baseline for several days: look at sleep, stress, alcohol, training load and early signs of illness.

Oura's help page takes the same view: compare your HRV with your own trends, not with other people.

What changes HRV from day to day?

HRV responds within hours to stressors and recovery. In a five-year dataset of 9 million morning measurements, RMSSD was about 12% lower after high alcohol intake, about 10% lower during sickness, and about 4.8% lower after hard training, compared with each person's usual values (Altini and Plews, 2021).

Factor	Typical change in morning RMSSD	Source
High alcohol intake the evening before	About 12% lower	Altini and Plews, 2021
Sickness	About 10% lower	Altini and Plews, 2021
Hard training the day before	About 4.8% lower	Altini and Plews, 2021
Luteal vs follicular phase	About 3.2% lower in the luteal phase	Altini and Plews, 2021
Rest day	About 1.6% higher	Altini and Plews, 2021

Source: Altini and Plews, Sensors 2021, within-person changes in morning RMSSD from a smartphone app.

The authors found that HRV is "a more sensitive but not specific marker of stress." In practice, HRV tells you that something changed, not what changed. You find the cause by looking at what else happened. We cover each lever in more detail in how to increase HRV, low HRV meaning and alcohol and HRV.

Slower factors matter too. HRV tends to be lower with higher body mass index. In the same dataset, average RMSSD was 69 ms in the normal BMI group and 56 ms in the obese group. Physical activity level showed a weak positive association with HRV (r = 0.21).

When and how should you measure HRV?

Measure HRV at the same time and in the same position each day, ideally right after waking or during sleep. Consistency matters more than the method. Morning readings and overnight averages are both valid, but they give different numbers, so do not mix them in one trend.

There are three common ways to measure:

Method	When	Typical metric	Notes
Overnight wearable (ring, watch, strap)	During sleep	RMSSD or SDNN	No effort needed. Values depend on sleep stages and the device's averaging window.
Morning spot reading (chest strap or phone camera)	1 to 5 min after waking	RMSSD	Controlled conditions. Needs a daily habit.
Background watch readings	Moments when you are still, during the day and night	SDNN (Apple Watch)	Readings taken at different times of day are harder to compare.

Source: device documentation (Apple HealthKit, Oura Help) and Altini and Plews, 2021.

You do not need a watch. A phone camera can record a morning RMSSD reading, see measure HRV with your iPhone camera. For overnight values, see HRV during sleep. If you use an Apple Watch, read Apple Watch HRV: how it is measured.

Tips for a clean morning reading:

1. Measure before coffee, exercise or checking messages.
2. Stay in the same position (lying or sitting) every day.
3. Breathe normally, the same way every day.
4. Stay still. Movement adds noise.
5. Skip a day rather than measure in very different conditions.

Why do HRV numbers differ between devices?

HRV numbers differ between devices because they use different metrics (RMSSD or SDNN), different recording windows (one minute, five minutes, a whole night), different times (morning, overnight, random) and different signal sources (ECG, wrist, finger or ring optical sensors). Each choice shifts the value, so the same person can see 35 ms on one device and 60 ms on another.

This is why a "good HRV score" depends on the device. Whoop, Oura, Garmin and Apple Watch users should compare their number with their own history on the same device. Switching devices means building a new baseline.

How do HRV and resting heart rate relate?

HRV and resting heart rate usually move in opposite directions. When resting heart rate is lower, HRV tends to be higher, and when resting heart rate rises, HRV tends to fall. Reading both together gives a clearer picture than either alone, because a change in both is less likely to be measurement noise.

Oura's help page notes that HRV "tends to be higher when resting heart rate is slower." In the Altini and Plews dataset, high alcohol intake was associated with a 6% rise in morning heart rate and a 12% drop in RMSSD. Sickness showed a similar pair: heart rate up about 6%, RMSSD down about 10%.

The two signals have different strengths. HRV showed larger relative changes, which makes it more sensitive. But the authors also report that "effect sizes were typically larger for resting heart rate," because resting heart rate is less noisy from day to day. A recovery score that combines both, compared with your own baseline, uses the strength of each. For the heart rate side, see resting heart rate by age and recovery score explained.

What does HRV mean for training decisions?

For training, HRV is most useful as a trend. A 7-day average that holds steady or rises during a training block is generally read as good adaptation. A 7-day average that falls for a week or more, together with poor sleep or a higher resting heart rate, is a common reason to reduce training load and recover.

Plews et al. (2013) summarize the research view: decreases and increases in vagal HRV indices "have been suggested to indicate negative and positive adaptations" to endurance training. They also caution that in elite athletes, both increases and decreases in HRV have been associated with poor adaptation, which is why they recommend long-term monitoring of each athlete.

The size of a normal training effect is small. Altini and Plews (2021) found morning RMSSD about 3% to 5% lower after hard or high-intensity sessions and about 1.6% higher after rest days. The drop after high-intensity training was similar across age groups. A single small dip after intervals is expected. A drop of 10% or more that lasts several days is more likely to reflect accumulated fatigue, poor sleep, alcohol or illness.

Use HRV as one input, not a rule. How you feel, your sleep and your training plan still matter. If you feel well and your HRV is a little low, a planned session is usually fine.

How Svanu uses HRV

Svanu uses HRV as one input to a morning recovery score. It compares this morning's HRV and resting heart rate with your own recent baseline, plus your sleep. The baseline starts as provisional after 3 nights and becomes full at 7. Every score shows its inputs and what moved it.

Svanu reads HRV from Apple Health, so it works with an Apple Watch and with other devices that sync to Apple Health. If you have no watch, you can take a camera HRV reading: put a finger on the rear camera and flash for 20 to 30 seconds. The app computes RMSSD and shows live heart rate during the reading. Camera readings are compared only with camera readings, never with the watch's overnight SDNN, because the two metrics are not comparable.

If your device does not write HRV, recovery uses resting heart rate and sleep instead. All scores are computed on the iPhone. You can see how this works on the Svanu home page, or read more in Apple Watch HRV.

The short answer

A good HRV is a stable or rising trend against your own baseline, measured the same way each day. Population averages give context: about 42 ms RMSSD for a 5-minute resting reading in healthy adults, lower with age, and higher in active people. Use them to understand your range, not to grade yourself.