Contents
Heart Rate Zone Calculator
Compare five arithmetic heart-rate bands using percentage of maximum heart rate or heart rate reserve. Supply your inputs and see the method's limits.
What This Calculator Does
This tool applies five percentage bands to the numbers you supply. It compares two methods; it does not measure your maximum heart rate, identify physiological thresholds or prescribe an exercise intensity.
| Method | Calculation at fraction p | Required inputs |
|---|---|---|
| Percentage of maximum | p × maximum HR | Maximum HR |
| Heart rate reserve (Karvonen) | resting HR + p × (maximum HR − resting HR) | Maximum and resting HR |
The bands use boundaries at 50%, 60%, 70%, 80%, 90% and 100%. The same percentage means a different number when its basis changes. Neither method is universally labeled more accurate here.
Reproduce the Comparison
Use maximum 180 bpm and resting 50 bpm as synthetic arithmetic inputs, not recommended personal settings.
- Percentage method, band 2: 180 × 0.60 to 180 × 0.70 = 108–126 bpm.
- Reserve method: reserve = 180 − 50 = 130; band 2 = 50 + 130 × 0.60 to 50 + 130 × 0.70 = 128–141 bpm.
The output rounds endpoints to the nearest whole bpm. Adjacent bands share a boundary; crossing it by one beat does not establish a physiological change.
Input Limits and Uncertainty
Maximum HR is required, within this calculator's input range of 120–220 bpm. Reserve mode additionally requires resting HR within 30–100 bpm. These are interface limits, not definitions of normal heart rate. Inputs must be whole numbers. Percentage mode does not use the resting field; reserve mode never substitutes a missing resting value.
Record whether the maximum you enter is an estimate or a value obtained through an appropriate assessment. A highest watch reading is not automatically your maximum. This tool does not provide an all-out self-test or determine whether such testing is suitable.
Threshold-based zone systems use different reference measurements. Do not enter a threshold heart rate as though it were maximum HR, or transfer these zone numbers into another system without checking its basis.
Use the Result in Context
For definitions, see the heart-rate zone reference. For applying readings during runs, see the heart-rate troubleshooting guide.
A calculated band does not guarantee adaptation, recovery or safety. A comfortable-looking number does not override how you feel, and an unexpected reading should not automatically be dismissed as sensor error.