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Navy body fat calculator

The Navy method estimates body fat from tape measurements alone. It is more informative than BMI and much cheaper than a DEXA scan.

At the navel for men, at the narrowest point for women.

Women only — at the widest point.

Body fat
16.94%
≈ Rounded Fitness
Fat mass
11.86
Lean mass
58.14
Show the working
  1. Sex = 1
  2. Height = 175
  3. Waist circumference = 85
  4. Neck circumference = 38
  5. Hip circumference = 95
  6. Weight = 70
  7. male = 1 = 1
  8. Body fat = 1 > 0 ? 495 / (1.0324 - 0.19077*log10(85 - 38) + 0.15456*log10(175)) - 450 : 495 / (1.29579 - 0.35004*log10(85 + 95 - 38) + 0.22100*log10(175)) - 450 = 16.938
  9. Fat mass = 70 * 16.938 / 100 = 11.8566
  10. Lean mass = 70 - 11.8566 = 58.1434

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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    The formula

    • Men: %fat = 495 / (1.0324 - 0.19077 log10(waist - neck) + 0.15456 log10(height)) - 450
    • Women: %fat = 495 / (1.29579 - 0.35004 log10(waist + hip - neck) + 0.22100 log10(height)) - 450
    • All circumferences in centimetres.

    The published formula is written for inches; this implementation uses the equivalent centimetre coefficients, which is why the constants differ from some versions you will see.

    Standard error against hydrostatic weighing is around 3 to 4 percentage points, so treat one decimal place as generous.

    The band labels are the American Council on Exercise ranges for men; women sit roughly eight points higher in every band.

    This is a population formula, not a diagnosis. Individual metabolism, body composition and medical history all move the real answer, so treat the number as a starting point and talk to a clinician about anything that matters.

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