Free public tool
Heart-Rate-Zone Calculator
Builds five training zones from a measured max heart rate when you have one, or the Tanaka estimate when you do not. Optional Karvonen mode anchors zones to heart-rate reserve.
Purpose & limitations
Age-estimated max HR carries a standard deviation of roughly ±10 bpm — a measured max from testing is always better. Beta-blockers and some conditions invalidate estimates entirely.
Inputs & validated ranges
| Input | Unit | Accepted range |
|---|---|---|
| Age (for estimate) | years | 18–100 |
| Measured max HR (overrides estimate) | bpm | 120–220 |
| Zone anchoring | choice | 2 options |
| Resting HR (Karvonen only) | bpm | 30–100 |
Formula & methodology
Estimated max HR = 208 − 0.7 × age (Tanaka). Zones at 50–60, 60–70, 70–80, 80–90, 90–100% of max HR — or of heart-rate reserve (max − resting) added back to resting HR in Karvonen mode.
Worked example
Age 35: max ≈ 208 − 24.5 = 183.5 bpm. Zone 2 = 110–128 bpm. Karvonen with resting 55: Zone 2 = 55 + (0.6–0.7)×128.5 = 132–145 bpm.
References
- Tanaka H, Monahan KD, Seals DR (2001). Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology. SourceMeta-analysis
- Karvonen MJ, Kentala E, Mustala O (1957). The effects of training on heart rate: a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae. SourceClassic study
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