How this calculator works
Maximum heart rate is estimated from age with one of four common formulas. Resting heart rate is either entered or counted: the number of beats in a period divided by the period in minutes gives beats per minute. Heart rate reserve is the gap between the two. The Karvonen method sets a training zone at a percentage of the reserve and adds the resting rate back, so zone 1 at 50 to 60 percent sits above rest rather than at half of maximum.
Formula
Maximum heart rate = the chosen age formula. Resting heart rate = beats / (seconds / 60). Reserve = maximum - resting. Zone bpm = resting + reserve x percentage / 100.
Worked example
A 35-year-old using Haskell and Fox has a maximum of 220 - 35 = 185 bpm. Counting 70 beats in 60 seconds gives a resting rate of 70 bpm and a reserve of 115. Zone 1 is 70 + 115 x 0.50 = 127.5 to 70 + 115 x 0.60 = 139 bpm. Zone 4 is 162 to 173.5 bpm.
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Frequently asked questions
Which maximum heart rate formula is best?
None is exact for an individual. Tanaka and Nes are often preferred in exercise science for their larger samples, while Haskell and Fox remains the familiar 220 minus age. A measured maximum from a hard test is better than any formula.
When should I measure resting heart rate?
Measure after waking and before getting out of bed, ideally over several days. A single reading can be affected by sleep, alcohol, illness and stress.
What is heart rate reserve used for?
It links the zones to both your maximum and your resting rate, so a fitter person with a lower resting pulse gets a different zone than an unfit person of the same age. It is the basis of the Karvonen method.