Health & Fitness

Body Fat Calculator

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

Last reviewed: How we build & verify
Body Fat %
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Category
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Fat Mass
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Lean Mass
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How it works

Estimates body fat percentage from tape measurements using the US Navy circumference method. It requires no equipment beyond a tape measure and is accurate to roughly ±3-4% against DEXA.

Formula
Men: %BF = 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
Variables
  • waistat the navel, cm
  • neckbelow the larynx, cm
  • hipat the widest point, cm (women only)
  • heightstanding height, cm
Worked example
Inputs: Male, waist 90 cm, neck 38 cm, height 180 cm
  1. waist − neck = 52 → log₁₀(52) = 1.716
  2. log₁₀(180) = 2.255
  3. Denominator: 1.0324 − 0.19077(1.716) + 0.15456(2.255) = 1.0538
  4. 495 / 1.0538 − 450 = 19.7
Result: ≈ 19.7% body fat
Notes
  • Women use a different equation that includes hip circumference: 495 / (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450.
  • Measure at the same time of day, unflexed, with the tape snug but not compressing. Consistency matters more than absolute accuracy for tracking.

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Frequently Asked Questions

Men: 10-20% is considered healthy (athletes 6-13%). Women: 18-28% is considered healthy (athletes 14-20%). The minimum fat needed for health is roughly 3% for men and 12% for women.

Circumference-based methods (US Navy method) are accurate to within ±3-4%. DEXA scans and hydrostatic weighing are the gold standard but require specialized equipment.

Body fat percentage is more accurate for individuals. BMI classifies muscular athletes as overweight. BMI remains a useful population-level screening tool because it is simple to measure.

Body Fat Calculator | ExaCalc