Body composition
Body fat estimate.
A tape measure and the same equations the U.S. Army and Navy use. Free, at home, in two minutes. It is an estimate, not a scan: how accurate it really is.
01
Use a non-stretch tape
Fiberglass or plastic, not cloth. Snug on bare skin, without pressing in.
02
Breathe out normally
Measure at the end of a relaxed breath out. Do not suck in.
03
Measure twice
Same spot, same time of day. Use the average of the two.
Method
Your measurements
The equations differ for men and women. Choose one to see what to measure.
The equations and sources
Army one-site (Army Directive 2023-11, the only Army tape method since June 2024). Men: −26.97 − 0.12 × weight (lb) + 1.99 × waist at the navel (in). Women: −9.15 − 0.015 × weight (lb) + 1.27 × waist at the navel (in). Source: Fort Jackson IG Update 23-4, which includes worked examples this calculator is tested against.
Navy tape (Hodgdon and Beckett). Men: 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Women: 163.205 × log10(waist + hips − neck) − 97.684 × log10(height) − 78.387, all in inches. These reproduce every value in the Navy's official estimation tables: Navy Guide 4, Body Composition Assessment (2016).
Results are estimates for adults. They are not a medical assessment. Metric measurements are converted to inches and pounds before calculating.