Fat-Burn Heart Rate Calculator
Quick answer: Your fat-burn zone is 60–70% of your maximum heart rate (American Council on Exercise convention). For example, a 40-year-old using the Fox formula (220 − age) has a max heart rate of 180 bpm, so the fat-burn zone is 108–126 bpm. Adding a resting heart rate of 65 bpm switches the math to the Karvonen method and gives a personalized zone of 134–146 bpm.
Find the heart rate range for your fat-burn zone in seconds. Enter your age, choose a max-heart-rate formula, and optionally add your resting heart rate to unlock the more personalized Karvonen calculation.
Enter your numbers
Your results
Estimate only — not medical advice. All max-heart-rate formulas are population estimates.
How to use this calculator
Enter your age and pick a max-heart-rate formula (Fox or Tanaka). If you know your resting heart rate — measured first thing in the morning before getting up — enter it too: the calculator then uses the Karvonen method on your heart-rate reserve, which personalizes the zone. The zone updates instantly as you change inputs.
How it works
Max heart rate: Fox = 220 − age; Tanaka = 208 − 0.7 × age. Without a resting heart rate, the fat-burn zone = 60–70% of max heart rate. With a resting heart rate, the Karvonen method is used: target = resting HR + percentage × (max HR − resting HR), where (max HR − resting HR) is your heart-rate reserve.
Worked example
Age 40, Fox formula: max heart rate = 220 − 40 = 180 bpm; fat-burn zone = 60% × 180 to 70% × 180 = 108–126 bpm. Add a resting heart rate of 65 bpm (Karvonen): heart-rate reserve = 180 − 65 = 115; zone = 65 + 0.60 × 115 to 65 + 0.70 × 115 = 134–146 bpm.
Reference data
| Formula | Equation | Published |
|---|---|---|
| Fox & Haskell | HRmax = 220 − age | 1971 |
| Tanaka | HRmax = 208 − 0.7 × age | 2001 (pooled 18,712 subjects) |
| Gulati (women) | HRmax = 206 − 0.88 × age | 2010 |
| Fat-burn zone | 60–70% of HRmax | American Council on Exercise convention |
Source: Fox, Naughton & Haskell (1971); Tanaka, Monahan & Seals (2001); Gulati et al., Circulation (2010); zone convention: American Council on Exercise (ACE), 2026.
Method & sources
Method: the calculator computes max heart rate with the chosen formula, then derives the 60–70% fat-burn zone either directly (percent of max HR) or via the Karvonen method when a resting heart rate is supplied. Every formula here is a population estimate: an individual's true maximum heart rate can differ substantially from any age-predicted value, so all outputs are estimates.
- Fox & Haskell (1971) — "Physical activity and the prevention of coronary heart disease."
- Tanaka, Monahan & Seals (2001) — "Age-predicted maximal heart rate revisited," Journal of the American College of Cardiology. jacc.org
- Gulati et al. (2010) — "Heart rate response to exercise stress testing in asymptomatic women," Circulation. ahajournals.org
- American Council on Exercise (ACE) — 60–70% of max heart rate fat-burn zone convention.
Frequently asked questions
What is the fat-burn heart rate zone?
The fat-burn zone is conventionally 60-70% of your maximum heart rate (an American Council on Exercise convention). A 40-year-old with a 180 bpm max heart rate has a fat-burn zone of 108-126 bpm.
What is the difference between the Fox and Tanaka formulas?
The Fox formula estimates max heart rate as 220 minus age, from Fox, Naughton & Haskell (1971). The Tanaka formula estimates 208 minus 0.7 × age, developed in 2001 from a pooled meta-analysis of 18,712 subjects. The calculator offers both; pick the one your training plan uses.
What is the Karvonen method?
The Karvonen method personalizes the zone using your resting heart rate: target = resting HR + percentage × (max HR − resting HR). Enter your resting heart rate and the calculator switches to Karvonen automatically.
Are these heart rate formulas accurate for everyone?
No. All max-heart-rate formulas are population estimates — an individual's true maximum can differ substantially from what any formula predicts. Treat every result as an estimate, not a medical measurement.
How do I check my heart rate during exercise?
Pause briefly and count your pulse for 15 seconds, then multiply by 4 — or use a heart-rate monitor, chest strap, or smartwatch for continuous readings during your workout.