How to measure
- Measure in the morning before eating, standing relaxed. Do not suck in.
- Neck: just below the Adam's apple, tape sloping slightly down to the front.
- Waist: men at the navel; women at the narrowest point, usually above the navel.
- Hips (women): around the widest part of the buttocks.
- Take each measurement twice and use the average. Re-measure every 2–4 weeks.
The formula
The US Navy method was developed by Hodgdon and Beckett at the Naval Health Research Center (1984) to screen personnel without lab equipment. It estimates body density from circumferences and height using log-based equations, then converts density to body fat percentage. The BMI-based figure uses the Deurenberg equation (1991), which knows nothing about muscle and will overestimate body fat for most lifters. That gap is exactly why the tape method is the better choice if you train.
Questions lifters ask
How accurate is the US Navy body fat method?
Studies comparing it with DEXA scans typically find errors of about 3–4 percentage points for individuals. It is consistent, though: measured the same way each time, it tracks change well, which is what most people need.
Where do I measure my waist and neck?
Men: waist horizontally at the navel, relaxed, not sucked in; neck just below the larynx. Women: waist at the narrowest point, hips at the widest point of the buttocks, neck below the larynx. Use a flexible tape that sits flat on the skin.
What is a healthy body fat percentage?
The American Council on Exercise lists 14–24% as fitness-to-average for men and 21–31% for women. Essential fat alone is 2–5% for men and 10–13% for women; going below that is unsafe.
What is the most accurate way to measure body fat?
DEXA and hydrostatic weighing are the reference methods, though each has a margin of error. Tape methods, skinfolds and smart scales are less accurate but fine for tracking trends if you measure consistently.