Free calculator

Heart Rate Zone Calculator

Enter your age (or your max heart rate if you know it). If you add your resting heart rate, we use the Karvonen method, which is more accurate.

How the zones are calculated

If you don't know your max heart rate, we estimate it with the Tanaka formula: 208 − 0.7 × age, which is more accurate than the classic 220 − age. With your resting heart rate we apply Karvonen: each zone is a percentage of your heart rate reserve (max − resting) added to your resting heart rate.

What each zone is for

Z1-Z2: your base. 75-80% of your weekly training should be here.
Z3: comfortably hard; useful, but don't overdo it.
Z4: threshold, intervals of 5-20 minutes.
Z5: short intervals at maximum intensity.

Frequently asked questions

What is my max heart rate?

The most reliable way to find it is an exercise stress test. Without one, 208 − 0.7 × age is a good estimate: at age 40, about 180 beats per minute.

Which zone burns the most fat?

In Z2 the share of fat you burn is high, but for weight loss what matters most is your total weekly energy expenditure and your diet.

Recommended gear

Chest heart rate strapMore accurate than wrist sensors during intervals.
Amazon Decathlon
Watch with heart rateTrain by zones without checking the calculator.
Amazon Decathlon

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