Body Fat Calculator

Estimate your body fat percentage using the US Navy circumference method. Includes BMI-based comparison, fat-mass and lean-mass figures.

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Tape measurements
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About the US Navy method

The US Navy circumference method estimates body fat using just a tape measure. It was developed by Hodgdon and Beckett in the 1980s and is still used by the US military for body composition assessments.

The formulas:

  • Men: %BF = 495 / (1.0324 − 0.19077·log₁₀(waist−neck) + 0.15456·log₁₀(height)) − 450
  • Women: %BF = 495 / (1.29579 − 0.35004·log₁₀(waist+hip−neck) + 0.22100·log₁₀(height)) − 450

The BMI-based estimate uses the Deurenberg formula: %BF = 1.20·BMI + 0.23·age − 10.8·sex − 5.4 (sex: 1 male, 0 female).

Frequently Asked Questions

The US Navy circumference method is typically accurate to within 3–4 percentage points for most adults compared with hydrostatic weighing or DEXA scans. It works best when measurements are taken correctly and is more accurate than BMI for athletic people.

Measure relaxed, with no clothing in the way. Neck: just below the larynx, tape sloping slightly downwards at the front. Waist: men measure at the navel, women at the narrowest part. Hips: women only, at the widest point of the buttocks. Don't pull tight – the tape should lie flat against skin.

For men, 14–24% is generally considered healthy (athletes 6–13%). For women, 21–31% is healthy (athletes 14–20%). Going below the "essential fat" range (men <6%, women <14%) is associated with health problems.

The Navy method uses circumference measurements that respond to actual fat distribution. The BMI-based (Deurenberg) estimate uses only height, weight, age and sex, so it overestimates body fat in muscular people and underestimates it in those with low muscle mass.
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Disclaimer

This calculator is for general fitness/educational purposes and is not a substitute for medical advice. Consult a healthcare professional before making changes to your diet or exercise routine, especially if you have existing health conditions.