Work out body fat (navy method) instantly with clear inputs, formula shown and shareable results.
The US Navy tape method estimates body fat from circumferences using logarithmic regressions - waist and neck for men, with hips added for women - plus height. An 85 cm waist, 38 cm neck and 178 cm height gives about 18% for a man. It typically agrees with hydrostatic weighing within 3-4 percentage points, and depends heavily on consistent tape placement.
Navy formula, men
%fat = 495 / (1.0324 - 0.19077 log10(waist - neck) + 0.15456 log10(height)) - 450
Navy formula, women
%fat = 495 / (1.29579 - 0.35004 log10(waist + hip - neck) + 0.221 log10(height)) - 450
These figures are population-average estimates, not a medical assessment or diagnosis. Body composition equations carry errors of several percentage points, and healthy ranges vary with age, ethnicity, muscularity and medical history. Discuss weight or body composition goals with a qualified clinician or dietitian.
Waist at the narrowest point for women and at navel height for men, neck just below the larynx, tape snug but not compressing.
Standard error of about 3-4 percentage points against DEXA. It tracks change over time well provided measurement technique stays constant.