Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Estimate body fat percentage using the official US Army circumference formula.
17.5%
This tool uses the US Army's own circumference-based body fat formula (per Army Regulation 600-9), which uses different coefficients than the Navy method -- an independently standardized approach, not a duplicate of the Navy formula.
Enter your sex, height, neck, and waist circumference (women also enter hip circumference). Your estimated body fat percentage appears instantly.
Men: 86.01 × log10(waist - neck) - 70.041 × log10(height) + 36.76
Women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387
Useful for anyone specifically wanting the Army's own body-composition standard rather than the Navy method (see the Body Fat Percentage Calculator) -- the two will typically give slightly different results for the same measurements, since they were independently derived.
Use a hypothetical man who is 70 inches tall with a 15-inch neck and a 34-inch waist, the same numbers the calculator starts with. The waist minus neck difference is 19 inches. The equation gives about 17.5 percent for those measurements. Running the same numbers through the Body Fat Percentage Calculator, which writes the same Navy circumference method as a density equation in centimetres, gives about 17.4 percent. The two agree to within a fraction of a point because they are the same method in two forms; the small gap comes from rounding in the published coefficients. Whichever you use, stay with one for tracking changes.
Every measurement is entered in inches: height, neck, waist, and, for women, hip. The waist must be larger than the neck so the logarithm in the equation is defined, all values must be positive, and the hip field appears only when the female option is chosen. The result is shown as a percentage to one decimal place and is floored at zero, so a nonsensical low measurement cannot show a negative figure. If your tape gives centimetres, divide by 2.54 first.
Men: 86.01 x log10(waist - neck) - 70.041 x log10(height) + 36.76
This tool reproduces a published circumference formula, but it is not an official assessment. Anyone who needs to meet a service standard must be measured by qualified personnel using the procedure and tables that apply to them, and those rules can differ from a quick self-measurement and can change over time. Check the current regulation and your unit's guidance rather than relying on a web calculator for a pass or fail decision. The results here are for personal information only.
As with any tape-based estimate, accuracy depends on body shape and measurement technique. People with unusually thick necks, very muscular builds or different fat distribution can see the figure deviate from a clinical scan. Treat the value as a rough guide, and speak with a doctor or registered dietitian if you have health concerns. This tool is educational only.
The two formulas were derived independently from different reference populations and use different coefficients -- some variation between them is expected and normal.
Yes -- this reproduces the circumference-based body fat formula published in Army Regulation 600-9.
Either is a reasonable field estimate; consistency (using the same method each time) matters more than which one you pick for tracking change over time.
No. Official assessments follow current rules and are done by authorized personnel. Use this only as a personal estimate and confirm requirements with your unit or the current regulation.
Both tools use the same circumference method, one as an inch and log10 equation and one as a centimetre density equation. Rounded published coefficients leave a gap of a few tenths of a point. Stick with one tool for tracking.
The tool floors the estimate at zero. It usually means your measurements do not fit the formula well, such as a very small waist minus neck difference.
Yes. When the female option is selected, a hip field appears and is used in the calculation.
Reference: Centers for Disease Control and Prevention