Heart rate zone calculator

Zone heart rate by Karvonen = resting HR + share × (max HR − resting HR). With a max of 190 and a resting rate of 60, zone 2, the aerobic zone, is 138–151 beats per minute.

Zone 2, aerobic base

138–151 bpm

How it adds up

Reserve 190 − 60 = 130. Zone 2: 60 + 0.6 × 130 = 138, 60 + 0.7 × 130 = 151

Five heart-rate zones

Zone	Heart rate, bpm	Share of reserve	What it trains
Zone 1, recovery	60–138	0 %–60 %	Warm-ups, cool-downs and easy days.
Zone 2, aerobic base	138–151	60 %–70 %	Long steady sessions for heart and muscle endurance. You can talk in full sentences.
Zone 3, aerobic power	151–164	70 %–80 %	Tempo work: breathing is faster, you talk in short phrases.
Zone 4, threshold	164–177	80 %–90 %	Threshold work: hard, but sustainable for tens of minutes.
Zone 5, anaerobic	177–190	90 %–100 %	Short all-out intervals for maximal oxygen uptake and speed.

The Karvonen formula

Karvonen and colleagues (1957) proposed setting effort from heart-rate reserve — the gap between max and resting heart rate: zone HR = resting + share × reserve.

The app does the same when it knows both rates: the five zone boundaries are 60, 70, 80 and 90 % of reserve. Resting heart rate makes the zones personal: it's lower in fit people, and the boundaries shift.

Worked example

Max 190, resting 60: reserve 130. Zone 2 starts at 60 + 0.6 × 130 = 138 and ends at 60 + 0.7 × 130 = 151 beats per minute.

Where to get your max heart rate

Your own reading is best: the highest heart rate in recent months on a hard interval, in a race or at the top of a climb. Age-based estimates can be off by ten beats or more for an individual, so they aren't used here.

A chest strap is more accurate than a wrist watch, which lags on sharp efforts. With heart conditions or medication that affects heart rate, a doctor sets your zones.

Programs for this goal

Frequently asked questions

How do I calculate heart-rate zones with Karvonen?

Subtract resting heart rate from max — that's the reserve. Zone HR = resting + share × reserve; for zone 2 the shares are 0.6 and 0.7. With 190 and 60 that's 138–151 bpm.

Which heart-rate zone burns fat?

There's no special zone. Lower zones use a higher share of fat for fuel, but higher zones burn more calories per hour. For weight loss the calorie deficit matters more; zone 2 is handy because you can train in it for a long time.

How do I find my max heart rate?

Look for the highest heart rate in your watch history from hard workouts or races. A max test is for healthy people only, after a warm-up; with heart conditions, only with a doctor.

Why are my zones different from my watch?

Watches often set zones as a percentage of max without resting heart rate. Karvonen accounts for resting heart rate, so its lower zones come out higher.

This is an estimate for healthy adults, not medical advice. With an illness, pregnancy or medication, talk to your doctor.