WorldCalcs

Body Fat Calculator

Estimate your body fat percentage using the U.S. Navy circumference method.

Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026

Estimated body fat

18.4 %

U.S. Navy circumference method. Estimate only — not a diagnosis.

This is a general estimate, not medical advice or a body-composition diagnosis. For an accurate assessment, see a healthcare professional. See our Disclaimer.

What is body fat percentage?

Body fat percentage is the share of your total weight that is fat, rather than muscle, bone, organs and water. It is often a more useful health indicator than weight or BMI alone, because two people of the same weight can carry very different amounts of fat. This calculator uses the US Navy method, which estimates body fat from a few tape-measure circumferences plus your height.

How it's calculated

The US Navy formula uses your height and your neck and waist measurements (plus hip for women). It is a logarithmic equation: for men, body fat % = 495 divided by (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450; women also include the hip measurement. It is quick and free, but it is an estimate; methods like a DEXA scan are more precise.

Example

A man who is 180 cm tall with a 40 cm neck and 90 cm waist has an estimated body fat of about 18.4%. A woman who is 165 cm tall with a 33 cm neck, 75 cm waist and 95 cm hip is about 26.9%.

All calculations happen in your browser. Nothing is sent, stored, or tracked.

Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer

How to use

Pick metric or imperial, select sex, then enter your height and tape measurements. Body fat percentage updates instantly.

Measure with a flexible tape, keeping it level and snug but not compressing the skin. Take each measurement two or three times and use the average.

Frequently asked questions

What is a healthy body fat percentage?+

It varies by age and sex; fitness ranges are often cited around 14 to 24% for men and 21 to 31% for women, but check with a professional.

How does the US Navy method work?+

It estimates body fat from height and circumference measurements (neck and waist, plus hip for women) using a logarithmic formula.

How accurate is it?+

It is a reasonable estimate for most people but less precise than a DEXA scan or hydrostatic weighing; measure carefully for the best result.

What is the difference between body fat and BMI?+

BMI uses only height and weight; body fat percentage estimates the actual proportion of fat. See our BMI Calculator.

How should I measure for accuracy?+

Use a flexible tape, measure relaxed and level, and take each measurement a couple of times.

Why do men and women use different formulas?+

Women typically carry more essential fat, and the formula adds the hip measurement to reflect this.

Can body fat be too low?+

Yes; very low body fat can harm health, since some essential fat is needed for normal function.

How can I reduce body fat?+

Through a sustained calorie deficit and activity; see our Calorie Calculator and BMR Calculator.

References

  • Hodgdon JA, Beckett MB. U.S. Navy circumference-based body-fat equations, 1984.

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