Health Formula • Published on September 01, 2026 • Last updated September 01, 2026
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Age in years
Estimated Maximum Heart Rate in beats per minute (bpm)
Resting heart rate in bpm, measured first thing in the morning before getting up
Desired training intensity as a decimal, typically 0.5-0.85 (50%-85%) for aerobic training zones
Calculating a target heart rate training zone actually involves two separate decisions: which formula to use for estimating Maximum Heart Rate (MHR), and then how to convert that MHR into an actual target zone. Haskell & Fox's "220 minus age" is the older, simpler, and most widely recognized MHR formula, but it was derived from a relatively small and non-representative sample.
Tanaka's formula (208 − 0.7×age) is a more recent, research-validated alternative developed from a meta-analysis of a much larger dataset, and tends to be considered more accurate, particularly for older adults. Once an MHR estimate is chosen, the Karvonen method converts it into a target heart rate by factoring in resting heart rate (via Heart Rate Reserve) rather than just applying a flat percentage of MHR, which produces more personalized training zones for people with different fitness levels.
Haskell & Fox (220 − age) is simpler and more widely known, making it fine for casual use. Tanaka (208 − 0.7×age) is generally considered more accurate, particularly for people over 40, since it was derived from a larger and more representative research sample and predicts a slightly higher max heart rate at older ages.
Two people with the same max heart rate can have very different fitness levels, reflected in their resting heart rate — a fitter person typically has a lower resting heart rate. By incorporating Heart Rate Reserve (MHR minus resting HR), the Karvonen method produces a target zone personalized to actual cardiovascular fitness, not just age.
Roughly 50-60% intensity corresponds to light aerobic activity, 60-70% to fat-burning/moderate zones, 70-85% to cardio/endurance training zones, and above 85% to high-intensity anaerobic training — the appropriate zone depends on individual fitness goals.
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