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Health & Fitness Calculators

Body Fat Estimator

Estimate body fat from a few tape measurements using the US Navy method. Measure at the narrowest point of the neck, the waist at navel level (men) or narrowest point (women), and the widest point of the hips (women).

Units
Sex
kg
cm
cm
cm
Estimated body fat18.7%
Category (ACE)
Average
Fat mass
14.6 kg
Lean mass
63.4 kg
Step-by-step working
  1. Men: 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
  2. All measurements in centimetres → 18.7%

Tape methods are typically within a few percentage points of lab measurements; technique matters more than precision.

How to use the Body Fat Estimator

  1. Choose units and sex.
  2. Measure neck, waist (and hips for women) with a flexible tape.
  3. Enter weight and height and press Calculate.

Formula

US Navy method (metric):

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

Categories (American Council on Exercise), men / women: essential 2–5 / 10–13, athletes 6–13 / 14–20, fitness 14–17 / 21–24, average 18–24 / 25–31, obese 25+ / 32+.

Examples

  • Man, 178 cm, neck 38 cm, waist 88 cm: ≈ 18.7%, in the average range.

Frequently asked questions

How should I measure?

Measure on bare skin in the morning, relaxed, without pulling in your stomach. Take each measurement twice and use the average.

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