Body fat calculator
Estimate your body fat percentage with a tape measure, using the U.S. Navy circumference method.
Your estimated body fat
Enter your measurements, then estimate.
How the estimate works
The Navy method predicts body density from circumferences and height, then converts density to percent body fat. In centimetres:
Female: 495 ÷ (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450
The equations differ by sex because average fat distribution differs, which is why women also need a hip measurement.
Worked example
A man is 178 cm tall with a 38 cm neck and an 85 cm waist. Waist − neck = 47 cm. Density = 1.0324 − 0.19077 × 1.6721 + 0.15456 × 2.2504 = 1.0612. Body fat = 495 ÷ 1.0612 − 450 = 16.4%, in the ACE “fitness” range of 14% to 17% for men. A woman, 165 cm tall, with a 33 cm neck, 75 cm waist and 98 cm hips works out to 28.4%, in the “average” range of 25% to 31%.
ACE descriptive ranges
| Description | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Higher body fat | 25% and above | 32% and above |
Limits
- It can differ from a DEXA scan by several percentage points, and small tape errors move the answer.
- It was built for general adult populations. People with very muscular necks or unusual body shapes may see bigger errors.
- The ranges describe groups. They are not a diagnosis, and very low values are not a goal.
Measure in the morning, the same way each time, and track the trend alongside waist-to-hip ratio.
Who this tool is for
This tool is for healthy adults aged 20 and older. It is not for use during pregnancy or breastfeeding, and it does not diagnose any condition, suggest medicine doses, set weight-loss targets or write personal meal plans. If you have a medical condition, or a result worries you, speak to a doctor or registered dietitian.
Your numbers stay in your browser. They are not sent anywhere, saved, or added to the page address. See our privacy policy.
Sources
- Hodgdon JA, Beckett MB (1984). Prediction of percent body fat from body circumferences and height. U.S. Navy, Naval Health Research Center — separate reports for men and women; check the originals for the coefficient tables
- American Council on Exercise (ACE): body fat percentage categories — descriptive ranges; confirm the current table on the ACE site
See the editorial methodology for how we check sources.