Heart rate variability (HRV) is the small variation in time between heartbeats. Wearables usually measure it overnight or in the morning and use it in recovery or readiness scores. HRV is highly individual, so compare against your own baseline rather than other people's numbers. A drop below your usual range can follow poor sleep, illness, alcohol or hard training.
HRV is one of the most talked-about wearable metrics.
How devices measure HRV
| Device | When it measures | Typical method |
|---|---|---|
| Smart rings | Overnight | RMSSD averages |
| Smartwatches | Overnight or spot checks | RMSSD or SDNN |
| Chest straps | During a set reading | Most accurate beat timing |
Reading your trend
- Wear the device consistently for a few weeks to build a baseline.
- Look at weekly averages, not single nights.
- Note what changes it: alcohol, late meals, stress, illness, training.
What HRV is not
HRV is a wellness indicator, not a diagnosis. See cleared vs wellness features.
Compare devices with smart ring vs smartwatch and check how accurate smartwatch heart data is. Browse smartwatches and trackers.
Common questions
What is a good HRV?
There is no single good number. HRV varies with age, fitness and genetics. Watch your own trend.
Why do my HRV numbers differ between devices?
Devices measure at different times and use different methods (such as RMSSD or SDNN). Compare within one device.
Can HRV diagnose health problems?
No. It is a general wellness measure. Talk to a doctor about symptoms or concerns.