What is HRV, and what’s a good HRV?

What is HRV, in plain words?

If your heart beats 60 times a minute, you might expect a beat exactly every second. It doesn’t work like that. One gap is a little shorter, the next a little longer, by a few hundredths of a second. HRV is a measure of how much those gaps vary.

Here’s what six beats might look like at about 60 beats a minute (an example, not real data):

Beat	Breath	Gap since the last beat
1	Breathing in	980 milliseconds
2	Breathing in	940 milliseconds
3	Breathing in	910 milliseconds
4	Breathing out	970 milliseconds
5	Breathing out	1,040 milliseconds
6	Breathing out	1,090 milliseconds

The average works out at about 61 beats a minute, but no two gaps are the same. A variable heart is a responsive one. As a 2017 review of HRV puts it, a healthy heart is not a metronome (Shaffer and Ginsberg 2017).

Why does your heart rate change with each breath?

Because of your vagus nerve. As you breathe in, it eases off and your heart speeds up slightly. As you breathe out, it brakes and your heart slows. This breathing rhythm in your heart rate has a name, respiratory sinus arrhythmia, and it’s normal and healthy (Shaffer and Ginsberg 2017).

Slow your breathing and the effect grows. At about 6 breaths a minute, the rise and fall with each breath is as large as it gets for most adults (Lehrer & Gevirtz 2014). You can feel it for yourself: put two fingers on your wrist and follow this breath.

What is a good HRV for my age?

A good HRV is the one that’s typical for you, at your age, measured the same way each time. That sounds like dodging the question, but the numbers really do depend on who you are and how they were measured.

Some honest reference points. A large review pooled short, roughly 5-minute recordings from 21,438 healthy adults. RMSSD, the measure most rings and straps use, averaged 42 milliseconds, with typical values from about 19 to 75 (Nunan et al. 2010). HRV falls steadily with age, so a healthy 60-year-old will usually sit well below a healthy 25-year-old (Shaffer and Ginsberg 2017).

You’ll find age charts online. Treat them loosely: overnight readings from a ring, morning readings from a strap and lab recordings aren’t interchangeable, and the same review warns against mixing norms from different recording lengths. The useful comparison is you against your own last few weeks.

Is a higher HRV better?

Usually, at rest. A higher resting HRV generally means the rest-and-digest side of your nervous system is doing more, and an optimal level is linked with health, adaptability and resilience. Across large groups of people, low HRV goes with higher health risks (Nunan et al. 2010).

But higher isn’t always better. Some heart rhythm problems, such as atrial fibrillation, make the gaps between beats irregular and push HRV readings up for the wrong reason (Shaffer and Ginsberg 2017). If your watch flags an irregular rhythm, that’s a conversation for your doctor, not an HRV win.

What does a low HRV mean?

Most often, that your body is working on something. Common reasons for a low reading:

One low morning means little. A downward trend over a couple of weeks is worth noticing.

Why does my HRV change from day to day?

Because it’s meant to. HRV reflects how your nervous system is balancing alert and rest, moment to moment, so it moves with sleep, food, drink, mood, temperature and even the position you’re in. Wearables smooth this out by averaging over the night or a few minutes after waking. Look at the weekly average rather than the daily score. The same goes for practice: Breathform’s History shows your minutes across the week, not just today’s.

How do watches measure HRV?

Most use a light sensor on your wrist or finger to time each pulse, then calculate how much the gaps vary. They take readings when you’re still, often during sleep, because movement blurs the signal.

Different devices use different maths. Apple Watch reports SDNN, which reflects variation over the whole recording. Many rings and straps report RMSSD, which looks at the change from one beat to the next and is the main measure of vagal, rest-side activity (Shaffer and Ginsberg 2017). A reading of 45 on one device and 45 on another may not mean the same thing.

Can breathing change HRV?

Yes, while you do it. A 2022 review of 223 studies found slow breathing raised HRV during practice, straight after a single session and after programmes lasting weeks (Laborde et al. 2022). Pace matters: in a lab test of 84 students, breathing at 6 breaths a minute raised HRV more than box breathing or 4-7-8 (Marchant et al. 2025).

So: slow breathing is the quickest, best-measured way to raise HRV in the moment. Whether it lifts your resting baseline depends on doing it regularly, for weeks. The how-to is in how to improve HRV with breathing, and the breath itself is coherent breathing. On a watch, the Apple Watch Breathe app paces the breath and tracks your heart rate as you go.

Every study on this page (6)

• Shaffer and Ginsberg, 2017: Review of HRV metrics and norms: RSA is the breathing-driven speeding and slowing of the heart via the vagus nerve; RMSSD is the main time-domain measure of vagally mediated HRV; HRV time-domain measures decline with age; higher HRV is not always better, since conditions such as atrial fibrillation can raise it; norms depend on age, sex and recording length and aren’t interchangeable.
• Lehrer & Gevirtz, 2014: Heart rate swings most at around six breaths a minute; this review says a blood-pressure reflex is the likeliest reason.
• Nunan et al., 2010: Systematic review of 44 studies (21,438 healthy adults) of short-term HRV: RMSSD averaged 42 ms (range 19–75) and SDNN 50 ms (range 32–93); HRV is a known risk factor for mortality in healthy and patient populations. Figures as tabulated in Shaffer and Ginsberg 2017.
• Laborde et al., 2022: Across 223 studies, slow breathing raised heart-rhythm signs of calm, during practice and after, though that alone doesn't prove a health benefit.
• Marchant et al., 2025: In 84 students, six breaths a minute raised heart-rhythm signs of calm modestly more than box or 4-7-8 breathing; none changed mood.
• Russo et al., 2017: An overview of research in healthy people suggests slow breathing affects the heart, lungs and nervous system; more study is needed.

Questions people ask

Is HRV the same as heart rate?

They’re related but different. Heart rate counts how many beats you have in a minute. HRV measures how much the gaps between those beats vary. When you’re relaxed, your heart is often slower and more variable at the same time, which is why the two numbers tend to move in opposite directions on your watch.

Is 30 a good HRV?

It can be. If your device reports RMSSD, 30 milliseconds sits well inside the range seen in healthy adults, which ran from about 19 to 75 in one large review of short recordings (Nunan et al. 2010). HRV falls with age, so lower numbers are common as you get older. What matters more is whether 30 is normal for you.

Should I worry if my HRV drops?

Usually not. A low day often follows a short night, a drink, a hard workout or a cold coming on, and it bounces back. A drop that lasts a couple of weeks is a nudge to look at sleep, stress and training. If you also have symptoms, such as palpitations, chest pain or breathlessness, see a doctor about those, not the number.

Is HRV different for men and women?

On average, yes, a little, and age matters even more. Reviews of HRV norms stress that age, sex, how long the recording lasts and how it was made all shift the typical values (Shaffer and Ginsberg 2017). That’s one more reason to compare your HRV with your own past readings, not with a friend’s.