Fat Burning Zone Calculator

Enter your age to find your maximum heart rate and the target heart-rate zone — about 60–70% of max — where fat is the main fuel your body burns.

Quick Facts

Method
Max HR = 220 − age; fat burning zone = 60–70% of max HR
Enter a resting heart rate to also get the more personalized Karvonen (heart-rate reserve) zone.

Your Results

Calculated
Fat burning zone
-
Target heart rate range (bpm)
Maximum heart rate
-
Estimated (220 − age)
Zone midpoint
-
Center of the range (bpm)
Karvonen zone
-
Uses resting HR, if provided

Ready

Enter your age and press Calculate.

What is the fat burning zone?

The "fat burning zone" is a range of exercise intensity — most commonly cited as 60% to 70% of your maximum heart rate — at which fat supplies the largest percentage of the calories you burn. At this moderate, comfortably-hard effort your muscles get plenty of oxygen, and aerobic metabolism can oxidize fatty acids efficiently. As intensity climbs toward your maximum, your body shifts toward burning carbohydrate (glycogen) because it is a faster-releasing fuel, so the fraction of energy coming from fat falls.

This calculator estimates that zone from a single number you already know — your age — and lets you also enter a resting heart rate for a more personalized estimate.

The formula

The calculation has two steps:

  • Maximum heart rate. The classic estimate is HRmax = 220 − age (the Fox formula). For a 40-year-old that gives 180 bpm.
  • Fat burning zone. Multiply your maximum heart rate by the lower and upper bounds of the zone. Using 60% and 70%: lower = HRmax × 0.60 and upper = HRmax × 0.70. For that same 40-year-old: 180 × 0.60 = 108 bpm and 180 × 0.70 = 126 bpm, so the fat burning zone is about 108–126 bpm.

If you enter a resting heart rate, the tool also reports the Karvonen (heart-rate reserve) zone: target = resting HR + (HRmax − resting HR) × intensity%. This accounts for your baseline fitness and usually gives a slightly higher, more individualized target.

Common reference points

  • Age 20 → HRmax ≈ 200 bpm → fat burning zone ≈ 120–140 bpm.
  • Age 30 → HRmax ≈ 190 bpm → fat burning zone ≈ 114–133 bpm.
  • Age 40 → HRmax ≈ 180 bpm → fat burning zone ≈ 108–126 bpm.
  • Age 50 → HRmax ≈ 170 bpm → fat burning zone ≈ 102–119 bpm.
  • Age 60 → HRmax ≈ 160 bpm → fat burning zone ≈ 96–112 bpm.

Does staying in the zone burn the most fat?

Not for total fat loss. The zone maximizes the percentage of calories from fat, but higher-intensity exercise burns more calories overall in the same time — and frequently more total grams of fat, plus more after-exercise calorie burn. The fat burning zone is genuinely useful for building an aerobic base, for long steady sessions, and for beginners who need a sustainable intensity, but for weight loss the bigger levers are total calories burned and overall diet.

Frequently Asked Questions

What is the fat burning zone?
It is the exercise-intensity range — usually 60% to 70% of your maximum heart rate — at which fat provides the largest share of the energy you burn. At this moderate effort your body has ample oxygen to oxidize fat efficiently, so proportionally more calories come from fat than from carbohydrate.
How do I calculate my fat burning zone heart rate?
Estimate your maximum heart rate as 220 minus your age, then multiply by the zone bounds. For a 40-year-old, HRmax ≈ 180 bpm, so the 60–70% zone is 180 × 0.60 = 108 bpm up to 180 × 0.70 = 126 bpm.
Does the fat burning zone burn the most total fat?
No. It burns the highest percentage of calories from fat, but higher-intensity workouts burn more total calories — and often more total fat — in the same amount of time. For overall fat loss, total energy expenditure and diet matter more than a specific heart-rate band.
How accurate is "220 minus age"?
It is a population average with a standard deviation of roughly ±10–12 bpm, so your true maximum could differ noticeably. More recent equations such as Tanaka (208 − 0.7 × age) fit older adults better. For a precise personal maximum, a supervised graded exercise test is the gold standard.

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