A good HRV is one that is normal for you, measured the same way each time. There is no single number that counts as good for everyone, because HRV depends on your age, your genes, your device and when you measure.
Good compared with what?
Before you judge a number, ask three questions.
Compared with whom? Healthy adults differ a lot. A review of 44 studies with 21,438 healthy adults, all measured with short resting recordings, found large differences from one person to the next. HRV also falls steadily with age. In data from more than 8 million Fitbit users, HRV went down as age went up. So a 25-year-old and a 60-year-old should not expect the same number.
Measured how? Apps report different statistics. Most show 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 , but some show 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 , and the two give different values for the same heartbeats. Recording length matters too. A review of HRV norms warns that values from 24-hour, 5-minute and shorter recordings are not interchangeable. The HRV by device guide shows what each brand reports.
Measured when? HRV changes across the day and night. The Fitbit data showed a strong daily rhythm. An average from your whole night will not match a two-minute reading taken after you get up.
Why your own baseline matters most
The most useful comparison is with yourself. Once you have a few weeks of readings, you know your usual range. A reading inside that range is a good reading for you. A reading well below it suggests your body is dealing with something, such as a short night, alcohol, hard training or a coming cold. See what a low HRV means for how to read a dip.
Higher is not automatically better either. In a study of 28,175 people who took a one-minute phone reading each morning, HRV was moderately linked with age and only weakly with physical activity. The authors concluded that aiming to raise your HRV may not be realistic for many people, given the role of genes and age. They found HRV more useful for spotting day-to-day changes in each person. The lesson why higher HRV is not always better covers the cases where a high number is not good news.
Is an HRV of 30 good?
It can be. Whether 30 ms is typical depends on your age, the statistic your app shows and when it measured. For one person it may be a normal night; for another it may be a dip. Two steps give you a fair answer:
- Look up age-matched values that were measured the same way. The normal HRV by age page has ranges with their conditions labelled.
- Compare it with your own 7-day average. If 30 is in your usual range, it is a good reading for you.
What to do with your own data
- Use one device and one routine, so your numbers stay comparable.
- Collect a few weeks of readings before you judge your 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 . The lesson on building your HRV baseline shows how.
- Watch the trend, not single days. A 7-day average smooths out normal ups and downs.
- If you want to support your HRV, focus on sleep, regular exercise and less alcohol. How can I increase my HRV? explains what helps and what to expect.
When to talk to a doctor
HRV cannot diagnose anything, and a low number on its own is not a reason to worry. Talk to a doctor if you have symptoms such as chest pain, fainting, shortness of breath or a racing or uneven heartbeat. The same goes for a large drop in HRV that lasts for weeks with no clear cause and comes with fatigue, poor sleep or feeling unwell.