Max heart rate & training zones
Training with a heart rate monitor and unsure where easy ends and threshold begins? This calculator estimates your maximum heart rate and splits it into five zones. Add your resting heart rate to make the zones more personal.
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How the calculation works
Your maximum heart rate is estimated with the well-known rule of thumb: 220 minus your age. It goes back to Fox and Haskell (1971) and is still the most widely used approximation.
With the rule of thumb, the zones sit at 50 to 60, 60 to 70, 70 to 80, 80 to 90 and 90 to 100 per cent of your maximum. If you choose Karvonen, the app uses your heart rate reserve instead: maximum minus resting heart rate. The percentages apply to that reserve and your resting heart rate is added back on. Fit people with a low resting heart rate get noticeably higher easy zones this way.
How to read the result
Zone 2 is for long, steady sessions where you can still talk in full sentences. Zones 4 and 5 are short and hard, for intervals.
Treat the numbers as a starting point. If a zone consistently feels wrong, your real maximum is probably somewhere else.
Frequently asked questions
How accurate is 220 minus age?
Not very, for any one person. A 2001 meta-analysis by Tanaka and colleagues proposed 208 minus 0.7 times age as a better fit, and even then many people are ten beats or more off. A lab or field test gives you your actual maximum.
When is Karvonen worth using?
When you know your resting heart rate. The method accounts for how far your heart rate can actually rise and usually gives fitter people more realistic easy zones.
How do I measure my resting heart rate?
Lying down, right after you wake up, for one minute. An average over several mornings is more reliable than a single reading.
Does this apply at altitude or in the heat?
Only partly. Altitude, heat, poor sleep or an infection all push your heart rate up at the same effort. On those days, go by feel rather than the zone.