Free calculator
HRV normal range calculator
There is no single “good” HRV. What matters is how your recent nights compare with your own normal. Paste 14 to 60 nights of Apple Watch HRV below to see your normal range and where your 7-day average sits in it. Everything runs in your browser; nothing is sent or saved.
Your HRV normal range
One value per night, separated by spaces, commas or new lines. Use the readings taken while you slept. 14 nights minimum; only the last 60 are used.
Still calibrating
Add 14 more nights. A normal range needs at least 14, and 60 is better.
Competo Readiness does this every morning from your Apple Watch, adds resting heart rate and sleep, and tells you whether today is the day to push in your competition.
Download CompetoNormal range = mean ± 0.5 standard deviations of ln(HRV) over your last 60 nights; 7-day average on the same log scale. Method from HRV-guided training research. An estimate for your own training decisions, not a health measurement.
How to get your nightly HRV from Apple Watch
On iPhone, open the Health app, tap Browse, then Heart, then Heart Rate Variability, and tap Show All Data. Apple Watch takes several readings a day; for this calculator, use one value per night: the reading (or the average of the readings) taken while you were asleep. Daytime readings move with whatever you were doing, which makes them much noisier.
Apple Watch reports HRV as SDNN in milliseconds. Most HRV research uses a different measure, rMSSD, taken in the morning. The two are related but not interchangeable, so compare your numbers only with your own past numbers, never with someone else’s or with a chart from another device.
How the normal range works
HRV is skewed: a few very high nights pull a plain average up. So the calculator works on the natural log of each value, which is what HRV-guided training studies do. Your normal range is the log-scale mean plus or minus half a standard deviation, converted back to milliseconds. Half a standard deviation is narrow on purpose: it is the size of change practitioners treat as meaningful rather than day-to-day wobble.
Worked example: 60 nights with a typical value of 45 ms and a log-scale spread of 0.151 give a normal range of about 41.7 to 48.5 ms. A single 49 ms night is above the range, but if the 7-day average is 47.5 ms it is still inside it, so nothing has really changed. Load the example nights above to see exactly that case.
The range moves with you. It uses only your last 60 nights, so a fitter, better-rested you gets a higher range over time, and a stretch of hard training or short sleep shows up as a 7-day average sliding toward the bottom of it.
What the result means for training and competing
In the HRV-guided training studies, athletes did their hard sessions when their HRV was inside or above their normal range and swapped them for easy ones when it dropped below. Those groups improved at least as much as groups that followed a fixed plan.
A weekly ring competition works the same way. On a below-range week, collect the points that cost little: close Stand, get your Exercise minutes with an easy walk, and save the big Move day for later in the week. When your average is back in range or above, that is the day to go after the person ahead of you.
Common questions
What is a normal HRV range on Apple Watch?
It is personal. Healthy adults differ widely, and age, genetics, fitness and the way HRV is measured all matter. The useful normal range is your own: about the middle of your last 60 nights, here the log-scale mean ± 0.5 standard deviations. With a typical value of 45 ms that is roughly 41.7 to 48.5 ms.
How many nights do I need?
At least 14 for a usable range; 60 is better because one unusual week matters less. The calculator always uses your most recent 60 nights.
Why use the 7-day average instead of last night?
A single night moves a lot with alcohol, a late meal, a warm room or how long you happened to be still while the watch measured. A 7-day average smooths that out, which is why HRV-guided training studies use rolling averages.
Is Apple Watch HRV SDNN or rMSSD?
SDNN. Apple’s HealthKit stores it as “heart rate variability SDNN”. Many other wearables and most training research use rMSSD, so numbers from different devices are not directly comparable.
Is a low HRV bad?
A low value compared with your own normal often follows hard training, short sleep, alcohol or getting sick, and usually comes back within days. A low number compared with someone else means very little. This calculator is not a health check; if you feel unwell or worried, talk to a doctor.
Does the calculator save my data?
No. The values stay in this page while it is open. Nothing is sent to a server or stored in your browser.
Sources
- Plews et al. (2013). Training adaptation and heart rate variability in elite endurance athletes. Sports Medicine 43(9).
- Vesterinen et al. (2016). Individual endurance training prescription with heart rate variability. Medicine & Science in Sports & Exercise 48(7).
- HRV4Training: daily score, baseline and normal range.
- Shaffer & Ginsberg (2017). An overview of heart rate variability metrics and norms. Frontiers in Public Health 5.
- Apple Developer: heartRateVariabilitySDNN (how HealthKit stores Apple Watch HRV).
Related
- Readiness on any Apple Watch
- What is a good HRV on Apple Watch?
- Apple Watch HRV vs Recovery HRV, and SDNN vs RMSSD
- Apple Watch competition points calculator
Not medical advice. Competo is independent and not affiliated with Apple. This calculator compares your numbers only with your own past numbers and is not a diagnostic tool.