CalcFitLab

Body Fat Calculator

U.S. Navy circumference method, no calipers.

Measure just below the larynx.

At the navel.

Body fat

16.1%

Fitness

U.S. Navy method

Reviewed by the CalcFitLab Editorial TeamUpdated 2026-08-01Read our methodology

How the body fat calculator works

This calculator estimates body fat percentage using the U.S. Navy circumference method, developed by Hodgdon and Beckett at the Naval Health Research Center in 1984. It needs only a tape measure: neck and waist for men, plus hip for women.

The method regresses body density from circumference ratios and height, then converts to fat percentage. Studies report it lands within about 3-4 percentage points of hydrostatic weighing for most people, which is good for a tape-only method.

Measure on bare skin, keep the tape snug but not compressing, and take each measurement twice. Small tape errors move the result, so consistency between check-ins matters more than any single number.

  • Men need neck and waist. Women also need the hip measurement.
  • Measure the waist at the narrowest point for women and at the navel for men, as the original protocol specifies.
  • Track the trend over weeks rather than fixating on one reading; measurement noise is real.

Frequently asked questions

Research puts it within roughly 3-4 percentage points of hydrostatic weighing for most people. It is less precise than a DEXA scan but far more accessible and repeatable at home.
Neck just below the larynx, waist at the navel for men and at the narrowest point for women, and hips at the widest point for women. Keep the tape level and snug.
The American Council on Exercise lists roughly 14-24% as the fitness-to-average range for men and 21-31% for women. Essential fat sits near 3-5% for men and 8-13% for women.