Body Fat Calculator | Tape Measure Method

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This tool produces a statistical adult estimate. It does not directly measure body fat and should not be used for diagnosis or treatment decisions.

Important method note: this calculator uses the 1984 Hodgdon–Beckett equations, widely known online as the classic “U.S. Navy tape method.” The U.S. Navy’s June 2026 official BCA procedure now uses a different height–waist–weight approach, so this is not an official current Navy BCA calculator.

Equation categoryThe original models use separate male and female coefficients.

Unit systemExisting measurements are converted automatically when you switch units.

Height (cm)Measure standing upright without shoes.

Neck circumference (cm)Measure just below the larynx without compressing the skin.

Waist / abdomen circumference (cm)Male equation: at the navel. Female equation: at the natural/narrowest waist.

Weight (optional) (kg)Does not affect body-fat percentage; used only for estimated fat mass and fat-free mass.

How is body fat estimated?

This calculator implements the classic circumference equations developed by Hodgdon and Beckett in 1984 for U.S. Navy personnel. The equations estimate body density from height and tape measurements, then convert density to an approximate body-fat percentage.

Male equation: Body fat % = 495 / [1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)] − 450

Female equation: Body fat % = 495 / [1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)] − 450

Lengths in these equations are centimeters. Imperial inputs are converted internally to centimeters. Body weight is not part of the percentage equation; it is used only to estimate fat mass and fat-free mass.

How should I take the tape measurements?

Height: measure standing upright without shoes.
Neck: measure just below the larynx, keeping the tape as horizontal as practical.
Male equation waist/abdomen: measure at the navel at the end of a normal relaxed exhale.
Female equation waist: measure at the natural or narrowest waist.
Female equation hip: measure around the widest protrusion of the hips, with the tape level.
The tape should contact the skin without compressing soft tissue; consistent placement matters because small differences can change the estimate.

This is an estimate, so the calculator does not assign “ideal,” “obese,” or other medical labels. The original U.S. Navy models reported standard errors of estimate of about 3.52 percentage points for men and 3.72 points for women; individual error can be larger. Tape placement, body shape and measurement technique all affect the result. The estimate should be treated especially cautiously for children, pregnancy, or situations that substantially alter body shape or fluid balance.

Method and current Navy procedure sources

Frequently asked questions

Is this the U.S. Navy’s current official BCA calculation?

No. This tool implements the classic 1984 Hodgdon–Beckett circumference equations. The U.S. Navy June 2026 Guide 4 uses a different height, waist and weight procedure for the current official BCA.

Why does the calculator not ask for age?

Age is not a variable in the classic Hodgdon–Beckett equations used here, so the tool does not request data that does not change the equation result.

Why is body weight optional?

The percentage equation does not use body weight. Weight is needed only to estimate fat mass and fat-free mass from the calculated percentage.

Why are the male and female measurements different?

The original equations were developed from separate reference samples. The male equation uses neck and waist/abdomen; the female equation also uses hip circumference.

Is this result medical advice?

No. It is a tape-measure-based statistical estimate and does not replace assessment by a qualified health professional.

Hesapica · Body Fat Calculator. The result is a tape-measure-based estimate, not a direct body-composition measurement or medical diagnosis.