Navy body fat calculator
Estimate body-fat percentage from tape measurements using the historical Navy circumference method. See what the number can and cannot tell you.
Your details
Sex-specific equations reflect the original research groups.
Enter total inches. For example, 5 ft 10 in = 70 in.
Measure just below the larynx, without compressing the skin.
Measure horizontally at the navel after a normal exhale.
A circumference-based estimate of body composition.
137.2lb
32.8lb
Lean mass includes more than muscle.
Water, bone, organs and other non-fat tissue are included. A change in this estimate does not, by itself, show muscle gain or loss.
Historical Hodgdon–Beckett method; not an official military assessment or a diagnosis. Tape placement and individual differences affect accuracy.
The numbers, explained.
Our methodology ↗This calculator implements the historical Hodgdon–Beckett circumference method. It estimates body density from height and tape measurements, then converts density to a body-fat percentage. Body weight is used only to convert that percentage into fat mass and lean mass.
For the male equation, enter neck circumference and abdomen circumference at the navel. The female equation uses neck, the narrowest natural waist and the widest part of the hips. These measurement locations are not interchangeable.
All tape measurements are converted to centimeters before evaluation. The logarithms are base 10. Some other calculators use a direct percentage regression instead of the density form; small differences between outputs can follow from the choice of equation.
This is a field estimate for adults, not a scan, diagnosis, fitness classification or current military pass/fail assessment. We do not assign “healthy” categories from this number. Repeatability and the limitations of the method matter more than the displayed decimal.
| Measurement | Where to measure |
|---|---|
| Neck | Just below the larynx |
| Male abdomen | Horizontally at the navel |
| Female waist | Narrowest natural waist |
| Female hips | Widest part of the buttocks |
D is estimated body density in g/cm³. All lengths inside the equations are centimeters. Not intended for pregnancy.
A little more clarity.
Is this the current official Navy assessment?
No. “Navy” here refers to the historical circumference equations. This site is not affiliated with the military and does not apply current service eligibility, rounding or pass/fail rules.
Does the calculator measure body fat directly?
No. It predicts body density from external measurements and converts that prediction into a percentage. Both steps rely on assumptions. A decimal place is display precision, not proof of accuracy.
Why is body weight required?
Weight does not enter the circumference-to-percentage equation. We use it to show estimated fat mass and lean mass. Changing only weight keeps the percentage the same but changes those two mass estimates.
What should I do if my measurements give an error?
Check the unit system and tape locations, then repeat the measurements. Negative circumference differences or implausible percentages are rejected rather than forced into a result.
Keep exploring.
All calculators ↗Methods checked against the linked references · September 14, 2026. Educational estimates for adults. No individual medical assessment.