About the Body Fat Calculator
Estimate body fat percentage with a tape measure, using the U.S. Navy circumference method. See your fat mass, lean mass and ACE fitness category.
Key features
- Body fat % with the U.S. Navy circumference method
- Only a tape measure needed: neck, waist (and hip for women)
- ACE body fat category
- Fat mass and lean mass
- Metric or imperial input
- Private: nothing leaves your browser
Estimate body fat with a tape measure
BMI only looks at height and weight. Body fat percentage tells you how much of your weight is fat, which is more useful for tracking fitness progress. The U.S. Navy method estimates it from a few simple circumference measurements.
The formulas (metric, cm)
Men: %BF = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: %BF = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450
Example
A man 178 cm tall with a 38 cm neck and an 86 cm waist: ≈ 17.2% body fat (Fitness category).
ACE body fat categories
| Category | Women | Men |
|---|---|---|
| Essential fat | 10–13% | 2–5% |
| Athletes | 14–20% | 6–13% |
| Fitness | 21–24% | 14–17% |
| Average | 25–31% | 18–24% |
| Obese | 32%+ | 25%+ |
Measuring tips
- Measure in the morning, before eating.
- Take each measurement three times and use the average.
- Use a flexible, non-stretch tape.
- Track the trend every 2–4 weeks, not day to day.
For general fitness information only, not medical advice.
Related calculators
Compare with your BMI, or plan nutrition with the Calorie Calculator.
How to use the Body Fat Calculator
- Enter your numbers in the fields above. Units and options can be changed at any time.
- The result updates instantly as you type; there's no calculate button to press.
- Check the breakdown under the main result for the details behind the number.
- Adjust the inputs to compare scenarios, for example a different rate or term.