Body Fat Calculator

History of Body Composition Measurement

Measuring body fat percentage evolved from simple girth comparisons to the circumference formulas used in fitness today.

Early Anthropometry

Nineteenth-century anthropometrists used tape measures and skinfold thickness to classify body types, long before lab-based body-composition testing existed.

Circumference-based estimates remained popular because they need only a tape measure.

The Navy Method

The U.S. Navy developed circumference equations in the 1980s to estimate body fat from height, neck, and waist (and hip for women) — accurate enough for military fitness standards without calipers.

The formula uses logarithms of these measurements to estimate body density and convert it to a fat percentage.

Modern Alternatives

Lab methods like DEXA, hydrostatic weighing, and bioelectrical impedance now offer more precise body composition, but the Navy method remains a free, accessible estimate.

This calculator implements the Navy circumference formula with standard category ranges.