Body composition

Calculate Body Fat Percentage

Estimate your body fat percentage with a tape measure: neck, waist and, for women, also the hips. You don't need anything more.

Sex

Directly below the larynx, tape tilted slightly downward at the front.

At navel height, relaxed after exhaling.

With this, the calculator also shows fat mass and lean mass.

Fill in the fields and the result appears right away.

Your inputs stay in your browser and are never sent anywhere.

How it works

The US Navy method estimates body fat percentage from body circumferences and height. Hodgdon and Beckett developed the formulas for the US Navy in 1984 and calibrated them against underwater weighing measurements.

For men, neck and waist are used, for women also the hips. The original formulas work in inches; the calculator converts centimeters internally.

If you enter your weight, the calculator also works out fat mass and lean mass in kilograms from the percentage.

How to use your result

Take the result as an estimate with a few percentage points of uncertainty. How well it fits you depends on your build and on how carefully you measure. With a very thick neck or a lot of belly fat, the formula can be clearly off.

The trend is most valuable. Always measure the same way: in the morning, before eating, with the same tape measure. If your waist circumference drops in a Cut, you are losing fat. If your weight rises in a Lean Bulk while your waist barely grows, you are mostly building lean mass.

You also need your body fat percentage for the FFMI calculator and for the protein range in a Cut.

Categories by ACE

CategoryMenWomen
Essential fat2 - 5 %10 - 13 %
Athletes6 - 13 %14 - 20 %
Fitness14 - 17 %21 - 24 %
Average18 - 24 %25 - 31 %
Obese≥ 25 %≥ 32 %

Formula and source

Men: body fat (%) = 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76
Women: body fat (%) = 163.205 × log10(waist + hips - neck) - 97.684 × log10(height) - 78.387
All measurements in inches (1 inch = 2.54 cm)
Fat mass = weight × body fat (%) ÷ 100, lean mass = weight - fat mass

Hodgdon JA, Beckett MB (1984): Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, San Diego, Reports 84-11 and 84-29. Categories after the body fat categories of the American Council on Exercise (ACE).

Frequently asked questions

It is an estimate. For groups it gives usable averages, for an individual it can be off by a few percentage points. It works well for tracking your trend if you always measure the same way.

Neck directly below the larynx. Waist for men at navel height, for women at the narrowest point. Hips for women at the widest point of the buttocks. The tape lies flat without digging in.

Scales with electrodes measure the electrical resistance of the body, which depends strongly on hydration. Both methods are estimates with their own errors. So only compare values within the same method.

Every two to four weeks is enough. Circumferences change slowly, and measuring too often mostly shows you measurement error.

All results are estimates and do not replace advice from a doctor or dietitian.

Related calculators

FFMI calculator Fat-free mass relative to height, after Kouri 1995. BMI calculator Body mass index, its categories and its limits for muscular people. Ideal weight calculator An estimated range from common formulas, clearly labelled as an estimate.