Target Heart Rate Calculator
Find your training heart rate zones using the Karvonen method, which accounts for resting heart rate rather than age alone.
How to use this calculator
- 1Measure your resting heart rate on waking, before getting out of bed, for the most accurate zones.
- 2Pick a maximum heart rate formula, or enter a measured maximum if you have had a proper test.
- 3Train the majority of your volume in Zone 2 and reserve Zones 4 and 5 for short, specific sessions.
How the calculation works
Target = Resting + Intensity × (Maximum − Resting)- Maximum − Resting
- Heart rate reserve — the range you actually train within
- Intensity
- Target percentage of that reserve, as a decimal
This is the Karvonen formula. The simpler alternative — a flat percentage of maximum — ignores resting heart rate and consequently prescribes zones that are too easy for fit individuals.
Tanaka (208 − 0.7 × age) was validated on a much larger sample than the 1970s 220 − age convention and is the better default.
Worked example
Age 35 with a resting heart rate of 65
- 1.Tanaka maximum: 208 − 0.7 × 35 = 183.5 bpm.
- 2.Heart rate reserve: 183.5 − 65 = 118.5 bpm.
- 3.Zone 2 lower bound: 65 + 0.60 × 118.5 = 136 bpm.
- 4.Zone 2 upper bound: 65 + 0.70 × 118.5 = 148 bpm.
Result: Zone 2 is roughly 136–148 bpm
What heart rate zones are trying to capture
Heart rate is a convenient, continuously available proxy for how hard the cardiovascular system is working, which is why structuring training around heart rate zones — rather than pace, power or perceived effort — became a mainstay of endurance coaching. Different intensity ranges are associated with different physiological adaptations: low intensities build aerobic base and favour fat metabolism, moderate intensities improve the body’s ability to clear lactate, and near-maximal intensities push VO₂ max, the ceiling on how much oxygen the body can use during exercise.
Two different ways to define “percent effort”
The simplest approach takes a flat percentage of estimated maximum heart rate. The Karvonen method used here instead works from heart rate reserve — the gap between resting and maximum heart rate — because it accounts for individual fitness in a way a flat percentage cannot. Two people can share the same maximum heart rate while one has a resting rate of 50 and the other 75; a flat-percentage method assigns them identical training zones, while Karvonen correctly gives the fitter, lower-resting-rate person a wider working range. The method is named for the Finnish physiologist Martti Karvonen, who described it in a 1957 exercise physiology study.
The zone system, broadly
Most zone-based training frameworks divide the heart rate reserve into five bands, from very light recovery effort up to short, maximal intervals, with the different zones intended to be trained in different proportions depending on the goal — most endurance programmes weight the majority of volume toward the easier zones, saving the hardest for a small fraction of total training time.
Why the number is an estimate, not a measurement
Every common maximum-heart-rate formula, including the widely used “220 minus age,” is a population regression with a real spread around it — commonly cited at roughly ±10–12 beats per minute — so any age-based maximum is a reasonable starting estimate rather than a precise personal ceiling. Heart rate is also influenced by factors that have nothing to do with fitness: heat, dehydration, caffeine, and several common medications, beta blockers in particular, can shift both resting and maximum heart rate enough to make age-based zones meaningfully wrong for that individual.
What this assumes, and where it stops
Assumptions
- The age-based maximum applies to you within its usual error range.
- Resting heart rate was measured properly — on waking, at rest.
Limitations
- Age-predicted maximum heart rate has a standard deviation of about 10–12 bpm, so individual error can be substantial.
- Beta blockers and several other medications lower both resting and maximum heart rate, invalidating these zones entirely.
- Heart rate lags behind effort, drifts upward over long sessions, and rises with heat and dehydration.
- Anyone with a cardiac condition should have training zones set by a clinician, not a calculator.
Common questions
Is 220 minus age accurate?
Not particularly. It originated as a rough fit in the 1970s and systematically overestimates maximum heart rate for younger adults while underestimating it for older ones. Tanaka’s 208 − 0.7 × age was validated on a far larger sample and is the better default, though every age formula carries around ±12 bpm of individual variation.
Why use heart rate reserve instead of a percentage of maximum?
Because it accounts for your resting heart rate. Two people with the same maximum but resting rates of 50 and 75 have very different working ranges, and a flat percentage of maximum prescribes identical — and therefore wrong — zones for both.
Sources
- Target heart rate and estimated maximum heart rate — US Centers for Disease Control and Prevention
Formula and content last reviewed on .
Results are estimates for information only, not professional advice.
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