Heart rate zone calculator
Work out five training zones from your age, resting rate and a maximum heart rate formula.
A clear answer. Here’s how.
Maximum heart rate comes from your chosen formula, or a tested value. Percent-of-maximum zones multiply it by each percentage. Karvonen zones add resting heart rate to each percentage of the reserve (maximum − resting). Zones run 50–60, 60–70, 70–80, 80–90 and 90–100 percent, rounded to whole beats. The age formulas are population averages with an individual spread of about ±10 bpm.
How this is checked
4 reference checks passed These 4 cases were run when this page was built, on 20 October 2026, and all reproduce within the stated tolerance. The same cases are part of the automated tests that run on every change to Toolmoz. Engine version 1.
See the checks and where each expected answer comes from
Case 1
- Inputs
- Age (years) 40Resting heart rate (bpm) 60Maximum heart rate source tanaka
- Expected, and what Toolmoz gave
- headline expected Maximum heart rate 180 bpm · reserve 120 bpm, Toolmoz Maximum heart rate 180 bpm · reserve 120 bpm
- Where the expected answer comes from
- Tanaka: 208 − 0.7 × 40 = 208 − 28 = 180 bpm; reserve = 180 − 60 = 120 bpm
- Allowed difference
- exact
Case 2
- Inputs
- Age (years) 30Resting heart rate (bpm) 60Maximum heart rate source fox
- Expected, and what Toolmoz gave
- headline expected Maximum heart rate 190 bpm · reserve 130 bpm, Toolmoz Maximum heart rate 190 bpm · reserve 130 bpm
- Where the expected answer comes from
- Fox: 220 − 30 = 190 bpm; reserve = 190 − 60 = 130 bpm
- Allowed difference
- exact
Case 3
- Inputs
- Age (years) 50Resting heart rate (bpm) 70Maximum heart rate source gellish
- Expected, and what Toolmoz gave
- headline expected Maximum heart rate 172 bpm · reserve 102 bpm, Toolmoz Maximum heart rate 172 bpm · reserve 102 bpm
- Where the expected answer comes from
- Gellish: 207 − 0.7 × 50 = 207 − 35 = 172 bpm; reserve = 172 − 70 = 102 bpm
- Allowed difference
- exact
Case 4
- Inputs
- Age (years) 40Resting heart rate (bpm) 55Maximum heart rate source measuredMeasured maximum heart rate (bpm) 185
- Expected, and what Toolmoz gave
- headline expected Maximum heart rate 185 bpm · reserve 130 bpm, Toolmoz Maximum heart rate 185 bpm · reserve 130 bpm
- Where the expected answer comes from
- A tested maximum of 185 bpm is used as given; reserve = 185 − 55 = 130 bpm
- Allowed difference
- exact
What this shows: the engine reproduces independently worked values for these cases. It does not prove every possible input is right. To test an answer you were given, see how to check a number; to see what is and is not checked across Toolmoz, see the accuracy ledger.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Age (years)
- 40
- Resting heart rate (bpm)
- 60
- Maximum heart rate source
- Tanaka: 208 − 0.7 × age
- Zone method
- Karvonen (heart-rate reserve)
Example result
| Zone | Intensity | % of heart-rate reserve | Lower bpm | Upper bpm |
|---|---|---|---|---|
| Zone 1 | Very light: warm-up and recovery | 50–60% | 120 | 132 |
| Zone 2 | Light: easy aerobic base | 60–70% | 132 | 144 |
| Zone 3 | Moderate: steady aerobic effort | 70–80% | 144 | 156 |
| Zone 4 | Hard: threshold work | 80–90% | 156 | 168 |
| Zone 5 | Maximum: short, very hard efforts | 90–100% | 168 | 180 |
Age-based maximum heart rate is an average with a spread of roughly ±10 bpm between individuals; a tested maximum is better. Karvonen zones add resting heart rate to a percentage of the reserve. Not medical advice: ask a clinician before intense exercise if you have a heart condition.