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Body fat percentage tells you what portion of your weight is fat — a far more meaningful measure of fitness than weight or BMI alone, because it separates fat from muscle. The US Navy method estimates it from a few tape-measure readings, no special equipment needed, making it a practical way to track body composition at home.
Enter your sex, height and circumference measurements, and your estimated body fat percentage is calculated instantly.
How is it calculated?
The US Navy method
The formula uses circumference measurements and height: - Men: based on waist − neck and height. - Women: based on waist + hip − neck and height.
It works because fat accumulates in predictable areas, so these circumferences correlate with total body fat. Measure snugly but without compressing the skin, ideally in the morning.
Healthy body fat ranges
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Women naturally carry more essential fat than men, which is why the healthy ranges differ.
Why it beats weight and BMI
Two people at the same weight can have very different body fat: a muscular person and an unfit person of equal weight sit far apart in health terms. Tracking body fat shows whether you're losing fat or muscle when you diet — the number that actually matters. Pair it with a waist-to-hip ratio calculator for a fuller picture.
Accuracy note
The Navy method is a good, repeatable estimate for tracking change over time, but it's not as precise as a DEXA scan or hydrostatic weighing. Measure the same way each time so your trend is meaningful.
Worked example
A man 180 cm tall with a 38 cm neck and a 92 cm waist: the US Navy formula gives an estimated body fat of about 21%, which falls in the "average" range for men. What makes this useful isn't the single number but the trend: if he measures again in six weeks and the waist has dropped while weight stayed flat, his body fat has fallen — meaning he lost fat and kept muscle, exactly the goal. That's insight a scale alone can never give.
FAQ
How is body fat percentage calculated?+
The US Navy method uses circumference measurements (neck and waist, plus hip for women) and height. It estimates body fat from where fat typically accumulates. Just enter your measurements.
What is a healthy body fat percentage?+
Roughly 14–24% for men and 21–31% for women covers fitness to average. Athletes are lower; above 25% (men) or 32% (women) is considered obese. Women naturally carry more essential fat.
Why is body fat better than BMI?+
BMI can't tell fat from muscle, so a muscular person may read "overweight." Body fat percentage separates the two, showing true body composition and whether you're losing fat or muscle.
How should I take the measurements?+
Measure snugly against the skin without compressing it, ideally in the morning. Take neck below the larynx and waist at the navel. Measure the same way each time for a reliable trend.
How accurate is the US Navy method?+
It's a good, repeatable estimate — excellent for tracking change over time — but less precise than a DEXA scan or hydrostatic weighing. Consistency of measurement matters more than absolute accuracy.
Why do men and women have different formulas?+
Women store more essential fat and in different areas, so the formula adds the hip measurement for women to capture body fat accurately across both.