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Target Heart Rate Calculator (Karvonen Method)

Calculate your target heart rate training zones from age and resting heart rate using the Karvonen heart-rate-reserve method.

Estimated max heart rate (bpm)
190
Heart rate reserve (bpm)
130
Zone 1 — Very light (50-60%)
125-138 bpm
Zone 2 — Light (60-70%)
138-151 bpm
Zone 3 — Moderate (70-80%)
151-164 bpm
Zone 4 — Hard (80-90%)
164-177 bpm
Zone 5 — Maximum (90-100%)
177-190 bpm

How it works

The Karvonen method estimates target heart rate from your heart rate reserve (HRR) — the gap between your maximum and resting heart rate — rather than a flat percentage of maximum alone, which makes it sensitive to individual fitness via resting heart rate. Estimated maximum heart rate uses the standard age-based approximation, maxHR = 220 − age, the same kind of widely used estimate as this site's Mifflin-St Jeor BMR formula, not a precise physiological measurement.

Each training zone's target range is restingHR + HRR × (percent ÷ 100), applied at the standard Karvonen zone breakpoints of 50/60/70/80/90/100% of heart rate reserve — the same five-zone breakdown (very light through maximum) commonly used in exercise physiology.

Resting heart rate must be lower than the estimated maximum heart rate for the formula to produce a meaningful, positive reserve.

FAQ

Why use heart rate reserve instead of a flat percentage of maximum heart rate?

A flat percentage of max heart rate (e.g. '70% of max') ignores resting heart rate entirely, so it gives the same target to a highly trained athlete with a low resting heart rate as to someone far less fit. The Karvonen method accounts for that difference by scaling the percentage against your own heart rate reserve instead.

How accurate is the 220 − age max heart rate estimate?

It's a population-average approximation with meaningful individual variation — some people's true maximum heart rate is well above or below what the formula predicts for their age. It's useful as a starting point for training zones, not a substitute for a measured maximum from an actual fitness test.

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