Army Body Fat Calculator

This calculator implements the official US Army tape test: a male-specific formula using waist, neck, and height, or a female-specific formula that adds hip circumference into the mix. The two formulas don't weigh their inputs the same way. In the male formula, Waist Circumference and Neck Circumference both sit inside the same log term (waist minus neck) -- a larger waist raises that term and a larger neck lowers it, and per inch their effects are comparable: at the calculator's defaults, +1 inch of Waist Circumference moves Body Fat Percentage by about +1.9 points while +1 inch of Neck Circumference moves it by about -2.0 points, so neck moves the result slightly more per inch, not less. Waist still produces the calculator's biggest real-world swing because its declared range (20-60 inches) is twice as wide as Neck Circumference's (10-30 inches), not because the formula favors it. In the female formula, Waist Circumference and Hip Circumference enter the same log term identically (waist + hip - neck), so a one-inch change in either moves the result by the same amount -- it's Hip Circumference's larger typical measurement (the calculator defaults to 38in hips vs.

34in waist) that makes it the bigger driver in practice, not any difference in how the formula treats them. In both formulas, Height and Neck Circumference pull the estimate down as they increase (a taller frame or thicker neck reads as leaner under this formula). Age doesn't touch the body fat calculation at all; it only sets which Army Standard percentage you're compared against, using four age brackets (17-20, 21-27, 28-39, 40+) that get progressively more lenient, with the female standards running about 10 percentage points higher than the male standards at every bracket. Hip Circumference only appears in the formula, and only in the UI, when Gender is set to Female -- for a male calculation it plays no role whatsoever. This is the same regression-based formula the Army uses for compliance screening, but applied outside a supervised tape-test setting; treat the result as an estimate, not an official measurement.