What this calculator works out
This calculator estimates your maximum heart rate from your age, then applies the lower and upper intensity percentages you choose to produce a training zone in beats per minute.
The estimate rests on the 220 minus age formula, which is convenient, ubiquitous and considerably less accurate than its popularity suggests. The result is a starting point for training, not a measurement of your physiology.
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Before you use the zone
- The defaults of 60% and 75% correspond broadly to moderate intensity aerobic exercise.
- Common zones are roughly 50–60% very light, 60–70% light aerobic, 70–80% moderate, 80–90% hard and 90%+ maximum.
- Individual maximum heart rates vary by 10 to 20 beats either side of any age formula. Two 40-year-olds can differ by 30 beats.
- Some medications, notably beta blockers, lower heart rate substantially and make these zones meaningless.
The talk test is free, needs no equipment and adapts automatically to heat, fatigue and illness. Moderate intensity means you can talk but not sing; vigorous means you can only manage a few words at a time. For most people this is more reliable than a zone derived from a population equation.
How this calculator works
An age-based maximum, then two percentages:
Estimated maximum = 220 − age
Lower bound = maximum × lower % ÷ 100
Upper bound = maximum × upper % ÷ 100
Tanaka alternative: maximum = 208 − (0.7 × age)Both formulas are shown because they diverge meaningfully outside middle age. At 40 they agree exactly at 180. At 20, 220 minus age gives 200 while Tanaka gives 194; at 60 it gives 160 against Tanaka's 166. The Tanaka equation was derived from a larger meta-analysis and is generally considered the better estimate.
A properly measured maximum requires a supervised maximal exercise test, which is not something to attempt alone.
Worked example: age 40 at 60 to 75%
Using the default figures — age 40, with a 60% to 75% zone:
- Estimated maximum: 220 − 40 = 180 bpm
- Lower bound: 180 × 60% = 108 bpm
- Upper bound: 180 × 75% = 135 bpm
At this age both formulas agree, which is a coincidence rather than reassurance — they cross at 40 and diverge in both directions. For a 25-year-old the two give maximums of 195 and 190.5, moving the top of the same zone by more than three beats. Against individual variation of 10 to 20 beats, that difference is minor; the honest reading of any of these numbers is "somewhere around", not a target to chase.
Common mistakes
- Treating the estimated maximum as measured. Individual variation is far wider than the difference between formulas.
- Chasing a zone during illness or heat. Heart rate rises for reasons unrelated to effort.
- Using zones while taking beta blockers. They lower heart rate and invalidate the calculation.
- Assuming a wrist monitor is accurate at high intensity. Optical sensors lose reliability as effort rises.
- Ignoring how you feel because the number says otherwise.
Frequently asked questions
How accurate is 220 minus age?
As a population average it is reasonable; as an individual prediction it is poor. Studies consistently find a standard deviation of 10 to 12 beats per minute, meaning a substantial minority of people sit 20 or more beats away from their predicted maximum. The Tanaka equation fits the data better but carries similar individual variation.
What intensity should I train at?
UK guidance recommends at least 150 minutes of moderate intensity activity a week, or 75 minutes of vigorous, plus muscle strengthening on two days. Moderate corresponds roughly to 60–75% of maximum heart rate. Most people benefit from a mix, with the majority of time at easier intensities.
Should I worry about a high heart rate during exercise?
Exceeding a formula-derived maximum is common and usually just means the formula was wrong for you. What warrants medical attention is chest pain, unusual breathlessness, dizziness, fainting or an irregular rhythm during exercise. Those are reasons to stop and see a GP regardless of what any number says.
Is resting heart rate more useful?
It is a more personal measurement, since you measure it rather than predict it. A resting rate that trends downwards over months often indicates improving aerobic fitness, and a sustained unexplained rise can signal illness, overtraining or stress. Measure it on waking, before getting up.
Is what I enter stored?
No. Age and percentages are processed in your browser and never transmitted or retained.
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References
- NHS — exercise intensity guidance and when to seek medical advice
- GOV.UK — UK Chief Medical Officers' physical activity guidelines
Sources are checked at publication and can change — how I choose and check references.