Enter neck, waist, height, and — for women — hip measurements to estimate body fat percentage using the US Navy circumference method.
How to Use the Body Fat Calculator
Select male or female first — the hip field only appears for women, since the men's version of the formula doesn't use it — then work through the tape measurements.
A scale can't tell fat from muscle — two people at the identical weight and height can have very different body compositions. This calculator estimates the split using tape-measure circumferences instead, following the method the US Navy has used for body composition screening since the 1980s.
Men: %BF = 495 ÷ (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450
Women: %BF = 495 ÷ (1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450All measurements in centimeters. Waist is measured at the navel, neck just below the larynx, and — for women — hip at the widest point. This is the US Navy circumference method, developed by Hodgdon and Beckett at the Naval Health Research Center in 1984 as a statistical fit against underwater weighing (the research-grade standard at the time), accurate to within a few percentage points for most people but less reliable at the extremes of body composition, where it tends to overestimate for very lean, muscular people and underestimate for people carrying weight in a pattern the original study sample didn't represent well.
Measurement technique matters more here than almost any other calculator on this site — a tape pulled too tight or measured at the wrong landmark shifts the result noticeably. Measure at the same time of day, without compressing the tape into the skin, for numbers that are at least consistent with each other over time.
An estimate, not a diagnosis. This formula approximates body composition from a handful of measurements — it isn't a substitute for DEXA scanning, hydrostatic weighing, or a clinician's assessment. Talk to a doctor about what your body fat percentage means for your health specifically.