Body Fat Calculator
Enter your height and a few circumference measurements to estimate your body fat percentage with the U.S. Navy method, and see where you fall in the adult reference categories. Works in metric or imperial units.
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What is body fat percentage?
Body fat percentage is the share of your total body weight that is fat tissue. Unlike BMI, which only uses weight, it distinguishes muscle from fat and is a useful measure of body composition.
This tool uses the U.S. Navy circumference method: measure your height, neck and waist (plus hips for women) with a tape, and the formula estimates your body fat percentage without special equipment.
How we calculate it
Men: body fat % = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450Women: body fat % = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450All measurements are in centimetres. The formula was developed by the U.S. Navy and is one of the most widely used equipment-free body fat estimates.
Adult reference categories
Based on American Council on Exercise (ACE) ranges for adults — the cutoffs differ for men and women:
Men
| Body fat | Category |
|---|---|
| 2 – 5% | Essential fat |
| 6 – 13% | Athletes |
| 14 – 17% | Fitness |
| 18 – 24% | Average |
| ≥ 25% | Obese |
Women
| Body fat | Category |
|---|---|
| 10 – 13% | Essential fat |
| 14 – 20% | Athletes |
| 21 – 24% | Fitness |
| 25 – 31% | Average |
| ≥ 32% | Obese |
Keep in mind
The circumference method is an estimate, not an exact measurement. Results can be affected by:
- How you measure — tape placement, tension and breathing all change the reading
- Fat distribution — the same measurements can map to different body fat on different people
- Athletes and very muscular people — the formula can overestimate body fat
- Older adults — body composition changes with age
Frequently asked questions
What is body fat percentage?
Body fat percentage is the share of your total body weight made up of fat tissue. It reflects body composition better than weight alone and is an important indicator of obesity and health risk.
How accurate is the U.S. Navy method?
It is one of the most common equipment-free estimates and is usually within about 3% for most people — but it is still an estimate. Exact measurement needs DEXA or professional equipment.
Are body fat standards different for men and women?
Yes. Women naturally carry more essential fat, so their healthy ranges sit higher overall. The calculator applies different cutoffs based on the sex you select.
What is a healthy body fat percentage?
For adult men, athlete level is around 6–13% and the healthy range is roughly 14–24%. For adult women, athlete level is around 14–20% and the healthy range is roughly 21–31%. Above that is the obese range.
How is body fat different from BMI?
BMI uses only height and weight and does not separate muscle from fat. Body fat percentage estimates fat directly, giving a truer picture of composition, but needs extra circumference measurements.
Does this calculator store my data?
No. All calculations run locally in your browser. Your measurements are never uploaded or saved.