Body Fat Percentage Calculator
Estimate body fat percentage using the U.S. Navy circumference method.
Written by Anil Gautam · Updated
Which measurements does the Navy method use?
The U.S. Navy method estimates body fat from height and tape measurements. For men the equation uses the logarithm of waist minus neck, for women the logarithm of waist plus hip minus neck, and both versions also use the logarithm of height. Hip size plays no part for men, which is why the hip slider appears only when you select Female.
All inputs are in centimetres. Height moves in 1 cm steps from 120 to 220, while neck (20 to 60 cm), waist (50 to 160 cm) and hip (70 to 160 cm) move in 0.5 cm steps. The result is shown to one decimal place and kept between 0 and 60%.
How much does one centimetre of tape change the result?
Because the equations use logarithms, the effect of a centimetre depends on your size. For a man with an 85 cm waist and a 38 cm neck, waist minus neck is 47 cm, and each extra centimetre of waist adds about 0.8 percentage points, while each extra centimetre of neck takes about 0.8 off. A woman with a 72 cm waist, 98 cm hips and a 32 cm neck has a combined figure of 138 cm, and one more centimetre on her waist or hips adds about 0.5 points.
A tape that sags or slips by a centimetre can therefore move you across a category line. Measure on bare skin with the tape level and snug without pressing in, take the waist after a normal breath out, and repeat each measurement until two readings agree. Measuring at the same time of day keeps comparisons from week to week fair.
What do the body fat categories mean?
The bands differ by sex because women carry more essential fat. For men the tool uses essential fat 2 to 5%, athletes 6 to 13%, fitness 14 to 17%, acceptable 18 to 24% and obese 25% or more. Women's bands are 10 to 13%, 14 to 20%, 21 to 24%, 25 to 31% and 32% or more, in the same order. Labels switch at whole-number thresholds, so a man at 17.9% reads Fitness and one at 18.0% reads Acceptable.
BMI Calculator works from height and weight alone, so it cannot separate muscle from fat, and a tape estimate adds information about where weight sits. For a daily calorie figure to go with it, use BMR & TDEE Calculator.