Body Fat Calculator

The U.S. Navy method

This free calculator uses the U.S. Navy circumference method, which estimates body fat from height plus neck, waist and (for women) hip measurements. For men: 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76. For women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387.

How to use

• Select your sex and enter height, neck, waist and, for women, hip in centimeters.
• Optional: add your weight to also get your fat mass in kilograms.
• Read your body fat percentage, ACE category and explanatory note.
• Check the category table below for men and women ranges.

FAQ

• How accurate is the U.S. Navy formula? When measured carefully, its error is typically around 3-4% compared with laboratory methods such as hydrostatic weighing. Keep measurements consistent and not too tight for the best result.
• What do the ACE categories mean? They follow the American Council on Exercise ranges: essential fat, athletes, fitness, average and obese. They are general guides and your ideal range depends on age, sport and personal goals.
• Why is the hip measurement only for women? Women store proportionally more fat around the hips and thighs, so the formula uses waist plus hip minus neck for them. Men can be estimated from the waist alone.