Running
Heart-Rate Zone Calculator
Build five Karvonen heart-rate zones from your age and resting heart rate.
Free · instant · no sign-upDeterministic
Result
Estimated max HR190bpm
Haskell: 220 − age.
Heart-rate reserve130bpm
Max − resting (Karvonen).
| Zone | Intensity | Heart rate (bpm) |
|---|---|---|
| Zone 1 | 50–60% — recovery | 125–138 |
| Zone 2 | 60–70% — endurance | 138–151 |
| Zone 3 | 70–80% — tempo | 151–164 |
| Zone 4 | 80–90% — threshold | 164–177 |
| Zone 5 | 90–100% — maximal | 177–190 |
Karvonen zones (% of heart-rate reserve, added to resting HR).
Age-based maximum is an estimate that varies by ±10–12 bpm between individuals.
The formula
Karvonen (heart-rate reserve)
zone = (HRmax − HRrest) × %intensity + HRrest
Source: Karvonen et al. (1957); Tanaka et al. (2001) for max-HR
What it means
- The Karvonen method scales zones to your heart-rate reserve, so they respect your resting fitness.
- Zones 1–2 build aerobic base; 3–4 raise threshold; 5 is maximal.
Limitations
- Age-based max HR is an estimate that varies by ±10–12 bpm.
- A measured max HR (from a hard test) gives better zones.
- Educational only — see a clinician before hard training if you have any heart condition.
Educational only
This calculator gives general, educational estimates about training and physiology — not personal, medical or nutritional advice. Numbers vary between individuals; check with a qualified coach or healthcare professional before acting on them.
Keep exploring
Follow the threads from this tool into the wider knowledge base.