How Does the Circumference Method Work?

This calculator estimates body fat percentage using simple tape measure readings of specific body parts — typically neck, waist, and hips (for women) or neck and waist (for men). The U.S. Navy developed this method as a practical alternative to expensive lab-based measurements.

While not as precise as DEXA scans or hydrostatic weighing, the circumference method is remarkably accurate for most people and requires only a tape measure. Studies show it correlates well with more expensive methods when measurements are taken correctly.

How to Take Accurate Measurements

Use a flexible tape measure pulled snug but not tight against the skin. Measure the neck just below the larynx, the waist at the narrowest point, and the hips at the widest point. Take each measurement twice and average them. Consistency in measurement location matters more than perfection.

FAQ

How accurate is this compared to a DEXA scan? Typically within 3–4% for most body types. It’s less accurate at extremes (very lean or very obese).

How often should I re-measure? Every 4 weeks gives enough time for meaningful change to be visible.