1-minute heart rate recovery calculator
Calculate the drop in your heart rate during the first minute after exercise.
HRV baseline calculator
Make sense of today’s HRV by comparing it with your own recent readings.
Your HRV readings
Example valuesUse previous daily readings from one device and HRV metric, in milliseconds.
No account needed. Calculations happen in your browser; your entries are not saved or sent to Century.
Example · Your recent baseline
50.0ms
Today is 10.0% below your recent average.
- Median
- 50.0 ms
- Recorded range
- 46–54 ms
7d
6d
5d
4d
3d
2d
1d
How it’s calculated
This tool uses the arithmetic mean of your previous readings as the baseline. Today’s difference is (today − baseline) ÷ baseline × 100. The median is the middle value after sorting, and the range is the lowest to highest reading. These describe the readings you enter; they are not a clinical normal range or Century’s recovery algorithm.
Reference: Apple HealthKit: HRV measurement (SDNN)
For general wellness information. This tool does not diagnose health conditions or replace medical advice.
Related tools
How to use your HRV baseline
Calculate a personal baseline from previous readings
An HRV baseline gives today’s reading a point of comparison. Enter seven previous daily values in milliseconds, then enter today’s value separately. Keeping today outside the baseline lets you see how it differs from the preceding week.
Use the same source, HRV metric and measurement routine for every entry. An overnight average and a short morning recording represent different sampling conditions. Comparing like with like makes this simple baseline easier to interpret.
Read the average, median and range together
The average uses every reading. The median is the middle reading after sorting and can help you notice when an unusually high or low value is pulling the average away from the centre of your recent values. The recorded range shows the lowest and highest entries; it is not a recommended range for your age.
A percentage below baseline describes a difference in the numbers you entered. It is not the percentage by which your recovery or fitness has fallen. Use the result as a starting point for looking at your recent pattern.
Use consistent Apple Watch, Garmin or Oura data
Check which HRV metric your device or app displays before copying readings. For example, Apple’s HealthKit documentation defines its SDNN quantity as the standard deviation of normal heartbeat intervals. SDNN and RMSSD are different measurements; this calculator does not convert between them.
Seven entries provide a recent snapshot rather than a permanent personal normal. Keep a longer history if you want to understand whether a change is unusual for you. Century brings available wearable signals into ongoing HRV and recovery trends without entering each value manually.
Frequently asked questions
How many days of HRV readings do I need?
This calculator needs seven previous daily HRV readings, plus today’s reading for comparison. Today is excluded from the baseline so it does not change the average it is being compared with. A seven-day baseline is a recent snapshot, not a long-term normal range.
What does HRV 10 percent below baseline mean?
It means today’s HRV is 90 percent of your recent average. For example, 45 ms compared with a 50 ms baseline is 10 percent below baseline: (45 − 50) ÷ 50 × 100 = −10%. This describes the difference; it does not establish its cause or tell you whether to exercise.
How do I calculate my HRV baseline?
Your HRV baseline is the average of seven previous daily HRV readings: add the readings and divide by seven. Use the same device and measurement method, then compare today’s separate reading with that average. Seven readings give a short snapshot; several weeks of consistent measurements provide more context.
Can I mix Apple Watch, Garmin and Oura readings?
Use one source and the same metric throughout. SDNN and RMSSD measure different aspects of variability and are not interchangeable. Keep the recording time and conditions as consistent as possible.
Is a higher HRV always better?
One number is not a verdict on recovery. Look at your own trend alongside sleep, recent activity and how you feel. This calculator does not tell you whether you should train or whether a reading is medically normal.
Does this calculate HRV from my pulse?
No. It summarizes HRV values already measured by your wearable, in milliseconds. It does not derive HRV from a heart rate reading or convert between HRV metrics.