Body Fat Calculator
Estimate your body fat percentage using the US Navy method with height, neck, waist, and hip measurements.
How to Use the Body Fat Calculator
- Select your gender — women will also see a hip measurement field.
- Measure your height, neck (below the Adam's apple), and waist (at the navel, relaxed).
- Women: also measure hips at the widest point.
- Click Calculate Body Fat for your percentage and category.
- Measure in the morning, relaxed, without sucking in, for consistent results.
Formula & Method
This calculator uses the US Navy circumference method (Hodgdon-Beckett, metric version — all measurements in centimeters):
Men: BF% = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450
Women: BF% = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450
Developed at the Naval Health Research Center in 1984, it estimates body density from circumference ratios and converts it to body fat percentage.
Examples
| Profile | Measurements | Body Fat | Category |
|---|---|---|---|
| Male, 178 cm | Neck 40, Waist 86 cm | ~16% | Fitness |
| Male, 175 cm | Neck 38, Waist 90 cm | ~21% | Average |
| Female, 165 cm | Neck 32, Waist 75, Hip 95 cm | ~27% | Average |
Frequently Asked Questions
What is a healthy body fat percentage?
For men: 14-24% is the healthy average range, 6-13% is athletic. For women: 21-31% is healthy average, 14-20% is athletic. Women naturally carry more essential fat.
How accurate is the Navy method?
Within about 3-4% of DEXA scan results for most people — excellent for a free method. Consistency of measurement matters more than the method.
Is BMI or body fat better?
Body fat percentage is more informative. BMI misclassifies muscular people as overweight. A muscular 90 kg man and a sedentary 90 kg man have the same BMI but very different body fat.
Where exactly do I measure my waist?
For men, at the navel level while relaxed. For women, at the narrowest point (usually above the navel). Do not suck in your stomach.
Can body fat be too low?
Yes. Below 6% for men and 14% for women risks hormonal problems, weakened immunity, and organ issues. Essential fat is exactly that — essential.
People Also Ask
What does 20% body fat look like?
For men, 20% shows some muscle definition with a soft midsection — no visible abs. For women, 20% is quite lean and athletic with clear muscle tone.
How fast can I lower body fat?
A safe rate is 0.5-1% per month with a calorie deficit and strength training. Faster loss usually sacrifices muscle, which lowers your metabolism.
Why do women need hip measurement but men do not?
Fat distributes differently by sex — women store more around hips and thighs, so the Navy formula includes hip circumference to capture that fat mass accurately.