How to measure
Neck
Just below the larynx (Adam's apple), tape sloping slightly down to the front.
Waist
Men: horizontally at the navel. Women: at the narrowest point, usually just above the navel. Breathe out normally, do not pull in.
Hips (women)
At the widest part of the buttocks, tape level.
Repeat
Measure twice, morning, before eating, and use the average. Re-measure every 2 to 4 weeks, not every day.
Body fat categories
| Category | Women | Men |
|---|---|---|
| Essential fat | 10 to 13% | 2 to 5% |
| Athletic | 14 to 20% | 6 to 13% |
| Fit | 21 to 24% | 14 to 17% |
| Average | 25 to 31% | 18 to 24% |
| Above average | 32% or more | 25% or more |
The formula
- Men: 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
- Women: 495 ÷ (1.29579 − 0.35004 × log10(waist + hips − neck) + 0.22100 × log10(height)) − 450
- All measurements in centimetres.
It is an estimate: DEXA scans, the reference, can differ by a few points, and bioimpedance scales vary with how much water you drank. What matters most is the trend: the same tape, the same place, every few weeks.
How to lower body fat
A small calorie deficit, enough protein (see the protein calculator) and two or three strength sessions a week. That combination keeps muscle while fat goes down, which is also why the scale can move slowly while your waist shrinks. For the basics, read how to lose weight calmly.
Questions about body fat
What is a healthy body fat percentage?
For adults, roughly 21 to 31% for women and 14 to 24% for men is common and healthy. Athletes are lower, and needs change with age.
How accurate is the US Navy method?
Usually within about 3 to 4 percentage points of lab methods for most people. Measuring carefully, at the same spots each time, matters more than the formula.
Is body fat better than BMI?
It tells you more about body composition, because BMI cannot separate muscle from fat. Use both, with your waist size.
How fast can I lose body fat?
About 0.5 to 1% of body weight a week is a realistic pace with a moderate deficit. Faster loss tends to take muscle with it.
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.
- American Council on Exercise. Percent body fat norms for men and women.
- Shaw K, et al. Exercise for overweight or obesity. Cochrane Database of Systematic Reviews, 2006.
This calculator gives general estimates, not medical advice. It is not suited to pregnancy, children or teens. For a precise measurement, ask a health professional.