Karvonen Target Heart Rate Calculator

About this calculator

The Karvonen method, developed by Finnish physiologist Martti Karvonen in 1957, calculates a target heart rate using heart-rate reserve (HRR) — the gap between your maximum heart rate and your resting heart rate — rather than a flat percentage of HRmax alone. The formula is: Target HR = ((HRmax − HRrest) × intensity%) + HRrest, so it personalizes the prescription to your actual cardiovascular fitness instead of just your age.

Because it accounts for resting heart rate, the Karvonen method is generally considered more accurate than the simple percent-of-HRmax method, especially for people whose resting heart rate is unusually low (very fit individuals) or high, where a flat-percentage zone can under- or overshoot true effort. Coaches, personal trainers, and cardiac rehabilitation programs use it to prescribe training zones for endurance work, interval training, and fat-burning versus VO2max-building efforts.

This calculator takes your age (or a directly entered HRmax), resting heart rate, and desired intensity percentage, and returns your target heart rate using the Karvonen formula so you know exactly what number to aim for during a workout.