Free Online Body Fat Calculator
Estimate body fat percentage with the US Navy method.
Measure the neck below the larynx and the waist at the navel. Keep the tape level and snug without compressing the skin.
This is an estimate, not a medical measurement. DEXA scans and hydrostatic weighing are more accurate. Body fat ranges differ by age, sex, and athletic background.
About the Body Fat Calculator
Body fat percentage is the share of your total body weight that comes from fat. Unlike the scale alone, it separates fat mass from lean mass, which includes muscle, bone, water, and organs. Two people can weigh the same and look very different because their body composition differs. This calculator estimates body fat with the US Navy circumference method, which uses a tape measure and a simple formula.
The US Navy method
For men, the formula uses neck and waist circumference plus height. For women, it adds hip circumference. The measurements are converted to centimetres and plugged into a logarithmic equation that estimates body density, which is then converted to a fat percentage. The method is popular because it needs only a tape measure, but it assumes a typical fat distribution. Very muscular people may be underestimated, and people with a different fat distribution may be overestimated.
How to measure
Measure the neck just below the larynx, with the tape sloping slightly downward at the front. Measure the waist at the navel for men, and at the narrowest point for women. Measure the hips at the widest point. Keep the tape level, snug, and parallel to the floor, and take each measurement two or three times for consistency. Use the same units throughout or let the calculator convert from imperial measurements.
Frequently asked questions
What is a healthy body fat percentage?
Common ranges are 8–19% for men and 21–32% for women, with athletes often lower and essential fat setting the minimum. Age and health history matter, so discuss your result with a professional.
Why do I need a hip measurement?
The female formula uses hip circumference because women tend to store fat around the hips, and including it improves the estimate. The male formula does not use hip measurement.
How accurate is the Navy method?
It is typically within a few percentage points of a DEXA scan for people with average builds. Accuracy drops for very lean or very muscular bodies and for people with atypical fat distribution.