How the Navy method works
Developed for US Navy fitness assessments, the method estimates body density from circumference ratios — waist and neck for men; waist, hip and neck for women — plus height. Accuracy is about ±3–4% against lab methods: not clinical precision, but free, repeatable, and more than good enough to track direction.
Measuring correctly
- Waist: at the navel (men) or the narrowest point (women), tape snug but not compressing, after a normal exhale.
- Neck: just below the larynx, tape sloping slightly downward at the front.
- Consistency rules: same time of day, same conditions, ideally the same person holding the tape.
A practical use of the result: feed it into the TDEE calculator as your body-fat input to unlock the Katch-McArdle formula, which estimates from lean mass.
Frequently asked questions
How accurate is the Navy body fat method?
Typically within ±3–4% of DEXA for most body types. It can read high on very muscular necks-and-shoulders builds and low on others — its real strength is tracking change over time with identical technique.
What is a healthy body fat percentage?
Commonly cited healthy ranges are about 10–20% for adult men and 18–28% for adult women, varying with age. Essential fat floors are ~3% (men) and ~12% (women) — going near them is for competitors, briefly.
How often should I measure?
Every 2–4 weeks. Day-to-day circumference shifts are mostly water and food volume; monthly trends are signal.
More calculators
TDEE Calculator
Work out your Total Daily Energy Expenditure
Calorie Calculator
Get a daily calorie target matched to your goal
BMR Calculator
Estimate the calories your body burns at complete rest, compared across the three standard equations
Calorie Deficit Calculator
Choose a weekly weight-loss rate and see the exact daily calories that achieve it
Macro Calculator
Split your daily calories into protein, carbs and fat
Maintenance Calorie Calculator
Find the daily calories that keep your weight stable
Sources
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center. 1984. [link]