Body Fat Percentage Calculator

Unlike BMI, which only looks at height and weight, the U.S. Navy method estimates body fat percentage from a handful of body circumference measurements, which makes it a noticeably better estimate of actual body composition without needing specialized equipment like calipers or a DEXA scan.

The method, developed for military fitness assessments, uses your height along with your neck and waist measurements (and hip measurement for women, since fat distribution differs by sex) plugged into a formula based on the mathematical relationship between body circumference and body density. For men, it's based on the difference between waist and neck measurements; for women, waist and hip measurements are combined and neck is subtracted, reflecting where body fat tends to accumulate differently between sexes.

Accuracy depends heavily on measuring correctly. Neck should be measured just below the larynx, waist at the narrowest point (or at the navel for a standardized measurement), and hips at the widest point around the buttocks, with the tape snug but not compressing the skin. Measuring at different points on different days, or letting the tape sag or pull tight, can shift the result by several percentage points.

Like any body fat estimate, the U.S. Navy method has known limitations: it tends to be less accurate for people at the extremes of body composition, very lean athletes or people with significantly higher body fat, and it doesn't distinguish between visceral fat (around organs, more health-relevant) and subcutaneous fat (just under the skin). It's a solid, equipment-free way to track changes over time using consistent measurements, but for a precise clinical reading, a DEXA scan or hydrostatic weighing test at a sports medicine or research facility remains the gold standard.