Target Heart Rate Calculator

Two ways to set a target zone

The percentage method is quick but ignores how fit you are. The Karvonen method works from heart rate reserve — the gap between resting and maximum — so a well-trained heart with a low resting rate gets a wider, more accurate working range. If you have measured your true maximum in a field test, use that instead of any formula: age-based estimates carry a standard deviation of roughly ten beats.

How to use the zones

Most endurance progress comes from spending the bulk of your weekly time in the light to moderate zones and only a small slice at the top end. Zone four and five work is potent but expensive to recover from, so one or two sessions a week is usually plenty. Measure your resting rate first thing in the morning before getting out of bed for the most stable reading.