Calculate your body fat %
Select gender and unit, measure with a tape (morning, relaxed, before eating), and enter the numbers. Your details stay in your browser — nothing is uploaded or stored.
Waist: narrowest point of the waist (men) or natural waistline (women). Neck: just below the Adam's apple. Hip: widest point around the buttocks.
How to use this calculator
1. Measure yourself in the morning with a soft tape: height, neck, waist, and hip (women only). 2. Pick your unit — cm or inches — the calculator converts automatically. 3. Press Calculate and read your body fat % plus your category. 4. Re-measure once a month under the same conditions to track your trend.
How it works
The US Navy method estimates body fat from simple tape measurements instead of skinfold calipers. For men it uses neck and waist; for women it adds the hip. The formulas: men = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76; women = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387.
Worked example: a man who is 178 cm tall with a 40 cm neck and 85 cm waist: 86.010 × log10(17.7) − 70.041 × log10(70.1) + 36.76 ≈ 14.9% — in the "Fitness" range for men. (The formula works on inch values; cm inputs are converted automatically.)
Frequently Asked Questions
What is a healthy body fat percentage? For men, a healthy range is roughly 14 to 24% (fitness to average); for women, about 21 to 31%. Below about 2–5% for men and 10–13% for women is essential fat — the minimum your body needs. Above 25% (men) or 32% (women) is classified as obese. These are general ranges; athletes and older adults sit in different bands.
How accurate is the US Navy body fat method? The US Navy method is one of the most accurate at-home estimates, typically within about 3 to 4 percentage points of DEXA or hydrostatic results when measurements are taken correctly. Consistency matters most: measure the same way, at the same time of day, to track real trends over time.
How often should I measure my body fat? Once a month is enough. Body fat changes slowly, and weekly measurements bounce around with water weight and digestion. Track monthly under the same conditions (morning, before eating) and watch the trend, not a single number.
How do I lower my body fat percentage? Sustain a modest calorie deficit (about 300 to 500 calories under maintenance), eat 1.6 to 2.2 grams of protein per kilogram of body weight daily, lift weights 2 to 4 times a week to keep muscle, and stay consistent. Aim to lose roughly 0.5 to 1% of body weight per week.
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