Body Fat Calculator

Estimate your body fat percentage, fat mass, and lean mass from tape measurements.

Years.

Weight
Height

Circumference in centimetres, measured just below the larynx.

Circumference in centimetres, at the navel.

Circumference in centimetres, at the widest point (women only).

Result—

Enter your values and calculate to see the result.

Formula used

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
(all measurements in cm)
fat mass   = weight(kg) × BF%
lean mass  = weight(kg) − fat mass
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Worked example

Woman, 30 yrs, 165 cm, neck 32 cm, waist 75 cm, hip 95 cm, 60 kg:

log terms → BF% ≈ 26.4%

Fat mass ≈ 60 × 0.264 = 15.8 kg, lean mass ≈ 44.2 kg.

Frequently asked questions

What method does this use?

The U.S. Navy circumference method, which estimates body fat percentage from height, neck, and waist (and hip for women) measurements in centimetres.

How accurate is the Navy method?

It is reasonably close for most people (within a few percent) but less precise than DEXA or hydrostatic weighing. It is best used to track trends over time, not for a single definitive reading.

Why does it ask for hip measurement only for women?

The Navy formula for women includes hip circumference; the male formula does not. The calculator shows or hides the hip field automatically based on the sex you select.

What do the categories mean?

They group body fat into ranges like athlete, fitness, average, and obese. The exact cut-offs differ for men and women. They are guides, not a diagnosis.

Should body fat replace BMI?

Body fat percentage describes composition; BMI only uses height and weight. They measure different things. Many people find body fat trends more meaningful than BMI alone.