Body fat calculator

What percentage of your weight is fat? A tape measure gets you a long way. Measure your neck and waist (and hips if you are a woman), enter your height and see your estimated body fat percentage.

Units

kg, cmlb, ft, in

Sex

MaleFemale

Height

Neck

Just below your Adam's apple.

Waist

At the level of your navel.

Weight

Your estimated body fat

16.1%

Category: fitness

Fat mass: 12.9 kg
Fat-free mass (muscle, bone, organs, water): 67.1 kg

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How to measure properly

Measure in the morning, before eating, standing relaxed and upright.
Keep the tape snug but not tight, and level (at your neck it may slope down slightly at the front).
Men measure the waist at the navel, women at the narrowest point (usually halfway between navel and breastbone). Breathe out normally and do not pull your stomach in.
Women measure the hips at the widest point of the buttocks.
Measure each spot two or three times and use the average.

The US Navy formula

In the 1980s the US Navy developed a way to estimate the body fat of service members with just a tape measure (Hodgdon and Beckett, 1984). The formula uses the fact that fat mostly builds up around your belly, while your neck is mostly muscle.

Male: % = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450

Female: % = 495 / (1.29579 − 0.35004 × log10(waist + hips − neck) + 0.22100 × log10(height)) − 450

All measurements in centimeters.

How accurate is it? It remains an estimate: compared with a scan the result can be a few percentage points off. More important than the exact number is the direction: measure the same way every few weeks and you will see whether you are losing fat.

What is a healthy body fat percentage?

Women naturally carry more fat than men. The American Council on Exercise uses these categories:

Body fat by category
Category	Men	Women
Essential fat	2–5%	10–13%
Athletes	6–13%	14–20%
Fitness	14–17%	21–24%
Acceptable	18–24%	25–31%
Obesity	25% and up	32% and up

You need essential fat to stay healthy; going lower is not healthy, not even for athletes.

Frequently asked questions

What is the most accurate way to measure body fat?

A DEXA scan at a clinic is the most accurate, but it costs money. A tape measure (this calculator) or a skinfold measurement by an experienced trainer are good free or cheap alternatives. Scales with electrodes are the least reliable: the result moves with how much you have had to drink.

Why is my result different from my scale?

Every method estimates in a different way and has its own error. So only compare results from the same method.

How fast can I lower my body fat?

With a small calorie deficit, enough protein and strength training, your body fat drops gradually without losing much muscle. Measure every two to four weeks.

This calculator gives an estimate for adults and is not a medical measurement.

Sources

Hodgdon, J.A. and Beckett, M.B. (1984). Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, reports 84-11 and 84-29.
Topend Sports: body fat from girth measurements (the metric formulas).
American Council on Exercise: percent body fat calculator and categories (archived, December 2023).

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