Maximum Fat-Burning Heart Rate Zone Calculator
Find the heart-rate zone where fat supplies the largest share of energy, using either %max heart rate or the Karvonen reserve method.
How it works
Max HR = 220 − age · %max method: zone = 60–70% × max HR · Karvonen: zone = resting + 60–70% × (max HR − resting)
At moderate intensity the body draws the largest proportion of its energy from fat; this “fat-burning zone” sits around 60–70% of maximum heart rate. Push harder and total calorie burn rises, but a bigger share comes from carbohydrate. The Karvonen method personalises the zone by anchoring it to your resting heart rate, so fitter people with lower resting rates get a slightly different target.
Worked example
At age 30 the maximum heart rate is 220 − 30 = 190 bpm. The %max fat-burning zone is 60–70% of 190 = 114–133 bpm, so the top of the fat-burning range is about 133 bpm.
Frequently asked questions
Does the fat-burning zone burn the most fat overall?
It burns the largest percentage of calories from fat, but higher-intensity work burns more total calories — and often more total fat — in the same time. For weight loss, total calories burned matters most.
Why does Karvonen give different numbers?
Karvonen uses your heart-rate reserve (max minus resting) rather than max alone, so a low resting heart rate — a sign of fitness — shifts the target zone. It is generally considered more individualised than the plain %max method.
Is 220 − age accurate for everyone?
It is a population average that can be off by 10–12 bpm for any individual. For precise training, a measured maximum from a graded exercise test is better than the age formula.
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Educational estimate only — not medical advice, diagnosis or treatment. Consult a qualified clinician for health decisions.