Karvonen Formula Calculator

The Karvonen method determines your target training heart rate (THR) by factoring in your Heart Rate Reserve (HRR), which is the difference between your maximum heart rate (MHR) and your resting heart rate (RHR). First, your maximum heart rate is estimated using the formula MHR = 220 - Age. Next, your Heart Rate Reserve is calculated as HRR = MHR - RHR. Finally, the target heart rate for any given workout intensity is calculated using the equation THR = (HRR * Intensity) + RHR, where intensity is expressed as a decimal.

Imagine a 30-year-old runner with a resting heart rate of 60 beats per minute (bpm) who wants to find their target heart rate for a 70% intensity endurance workout. First, calculate their maximum heart rate: MHR = 220 - 30 = 190 bpm. Second, determine their heart rate reserve: HRR = 190 - 60 = 130 bpm. Finally, apply the Karvonen formula for a 70% intensity level: THR = (130 * 0.70) + 60 = 91 + 60 = 151 bpm. Therefore, their target training heart rate for that session is 151 beats per minute.

Always measure your resting heart rate first thing in the morning before getting out of bed for the most accurate baseline. Remember that formulas like 220 minus age provide a population average; if your actual tested maximum heart rate differs significantly, use your measured value for better precision. Re-calculate your zones every few months as your cardiovascular fitness improves and your resting heart rate drops.