Body Fat Percentage Calculator
Use standardized tape measurements for a transparent U.S. Navy body-fat estimate and practical reference category.
Your Body Fat Percentage Result
Result status:
Practical interpretation
Important: Estimate only—not medical advice.
How the Body Fat Percentage Calculator works
Formula: Male: 86.010 × log10(abdomen in − neck in) − 70.041 × log10(height in) + 36.76. Female: 163.205 × log10(waist in + hip in − neck in) − 97.684 × log10(height in) − 78.387.
Canonical centimeters are converted to inches before Math.log10 is applied. For males, measure abdomen at the navel and ignore hip. For females, measure the natural waist and require hip at its widest point. For everyone, measure neck just below the larynx with a level, snug tape.
Assumptions and limits: Tape technique and population fit affect accuracy. Positive log geometry and a finite result strictly between 0% and 100% are required; invalid results are rejected rather than clamped. Results are estimates for education and planning, not medical advice.
ACE sex-specific body-fat reference categories
| Reference category | Male | Female |
|---|---|---|
| Below essential-fat reference | Below 2% | Below 10% |
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| High | 25% or higher | 32% or higher |
How to use your result
Use the result as a starting point, not a pass-or-fail score. Keep your inputs consistent, observe relevant trends over time, and adjust only when the trend—not one day—shows the estimate does not fit your needs.
Body measurements and equation-based targets always contain uncertainty. If your result conflicts with symptoms, a diagnosis, medication guidance, pregnancy needs, an eating-disorder recovery plan, or instructions from your care team, follow your qualified health professional.
Frequently Asked Questions
How should I measure for the Navy body-fat formula?
Use a level, snug tape without compressing skin. Measure the male abdomen at the navel, the female waist at its natural narrowest point, hips at the widest point, and neck just below the larynx.
Why is hip circumference marked optional?
The female equation requires hip circumference. The male equation does not use it, so a male result is valid when hip is blank and ignores a supplied hip value.
Can I use centimeters or inches?
Yes. Centimeters and inches are equivalent choices; the calculator converts circumference and height to the units required by the same formula.
What does the category mean?
It is a practical comparison with the displayed ACE sex-specific reference table. The unrounded estimate is classified before the percentage is rounded for display.
Is circumference body fat a direct measurement?
No. It is an anthropometric estimate derived from population data, not a scan, diagnosis, or direct measurement of fat tissue.
Why might the result be rejected?
The logarithmic geometry must be positive, and the calculated percentage must be finite and between 0% and 100%. Recheck tape locations and entered values rather than treating a clamped number as valid.
How should I track change?
Repeat measurements under similar conditions with the same tape position and tension. Small differences can reflect technique rather than a true body-composition change.
Is this body-fat result medical advice?
No. Categories are non-diagnostic references. Seek qualified guidance if body composition is relevant to symptoms, treatment, pregnancy, growth, or eating-disorder care.
Scientific References
- Guide 4: Body Composition Assessment U.S. Navy Physical Readiness Program
- Prediction of percent body fat for U.S. Navy men and women from body circumferences and height Defense Technical Information Center
- Accuracy of anthropometric equations for estimation of body fat in healthy adults American Journal of Clinical Nutrition
- Percent Body Fat Calculator American Council on Exercise