Calculate your body fat percentage
Find your body fat percentage, fat mass and lean mass in seconds — using the US Navy method, the most accurate formula available without lab equipment.
What does body fat percentage mean?
Body fat percentage is the proportion of your total body weight that is made up of fat tissue. It is a more accurate measure of body composition than BMI — because BMI only considers height and weight, while body fat percentage distinguishes between fat mass and lean mass (muscle, bone, water and organs).
Two people with identical height and weight can have very different body fat percentages — and very different health profiles. A 75 kg person with 15% body fat carries 11 kg of fat and 64 kg of lean mass. The same person at 30% body fat carries 22.5 kg of fat and only 52.5 kg of lean mass.
Body fat percentage categories
The American Council on Exercise (ACE) defines these ranges for healthy adults:
Men
Minimum for organ function. Not sustainable long-term.
Typical for competitive athletes and very lean individuals.
Visibly lean with some muscle definition. Healthy range.
Normal for most healthy adult males.
Associated with increased metabolic health risks.
Women
Minimum for hormonal and organ function.
Typical for female athletes and very lean individuals.
Visibly lean and healthy. Good body composition range.
Normal for most healthy adult females.
Associated with increased metabolic health risks.
How this calculator works — US Navy Method
This calculator uses the US Navy circumference method (Hodgdon & Beckett, 1984) — the most accurate body fat formula available without lab equipment or body fat calipers. It requires three measurements for men and four for women.
| Sex | Measurements required | Formula |
|---|---|---|
| Male | Height · Neck · Waist | 495 ÷ (1.0324 − 0.19077 × log(waist−neck) + 0.15456 × log(height)) − 450 |
| Female | Height · Neck · Waist · Hip | 495 ÷ (1.29579 − 0.35004 × log(waist+hip−neck) + 0.22100 × log(height)) − 450 |
Accuracy is within ±3–4% of DEXA scan results for most adults when measurements are taken correctly. The most common source of error is measuring waist at the wrong point — always measure at the narrowest point (navel level), not at the widest.
How to measure correctly — 3 steps
Neck
Measure just below the larynx (Adam’s apple), with the tape sloping slightly downward at the front. Do not flex or tense the neck. Round up to the nearest 0.5 cm.
Waist
Measure at the narrowest point — usually at or just above navel level. Keep your stomach relaxed. Do not suck in or tense your abs. This is the most important measurement for accuracy.
Hip (women only)
Measure at the widest point of the hips and buttocks, with feet together. Keep the tape horizontal and parallel to the floor.
Body fat percentage vs BMI — what is the difference?
| Metric | What it measures | Limitation |
|---|---|---|
| BMI | Weight relative to height | Cannot distinguish fat from muscle — a lean athlete and an obese person can have identical BMI |
| Body fat % | Fat mass as a proportion of total weight | Circumference method has ±3–4% error; most accurate non-lab measurement available |
For most people, body fat percentage is a more actionable number than BMI — it tells you whether you need to lose fat, gain muscle, or both. Pair it with our BMR calculator and calorie deficit calculator to build a plan around your actual body composition.
How to use your result
- High body fat (above average): Focus on a moderate calorie deficit of 300–500 kcal below TDEE, with high protein intake to preserve muscle. Use our calorie deficit calculator to set your daily target.
- Average body fat (maintaining): Focus on resistance training to improve body composition — increasing lean mass lowers body fat percentage without necessarily losing weight.
- Low body fat (athlete range): If you are gaining muscle, expect body fat percentage to stay stable or increase slightly as total mass increases — this is normal and not a sign of poor progress.
- Retest every 4–8 weeks: Body fat percentage changes more slowly than weight. Taking measurements at the same time of day, under the same conditions, gives the most consistent tracking data.
Frequently asked questions
How accurate is this body fat calculator?
The US Navy method is accurate to within ±3–4% of DEXA scan results for most adults when measurements are taken correctly. The most common source of error is an incorrectly measured waist — always measure at the narrowest point with the stomach relaxed, not sucked in.
What is a healthy body fat percentage?
For men, the healthy range is generally 14–24%. For women, it is 21–31%. Athletes typically sit at 6–13% (men) and 14–20% (women). Essential fat — the minimum required for basic organ function — is 2–5% for men and 10–13% for women. Going below essential fat levels is dangerous and not sustainable.
Is body fat percentage better than BMI?
For most purposes, yes. BMI cannot distinguish fat mass from muscle mass — a lean 90 kg athlete and a sedentary 90 kg person have the same BMI but very different health profiles. Body fat percentage directly measures what matters: how much of your body weight is fat versus lean tissue.
How often should I measure my body fat?
Every 4–8 weeks is sufficient for tracking progress. Body fat percentage changes slowly — checking too frequently creates noise rather than meaningful data. Measure at the same time of day (morning, before eating) and under the same conditions for the most consistent results.
Can I lose fat and gain muscle at the same time?
Yes — this is called body recomposition and is most achievable for beginners, people returning to training after a break, or anyone with higher body fat. It requires eating near TDEE (not in a large deficit), high protein intake (2g+ per kg bodyweight) and consistent resistance training. Progress is slower than either pure fat loss or pure muscle gain, but sustainable long-term.
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