Body Fat Percentage
Understand your body composition. Go beyond the scale.
Body composition estimate
Based on the optional 70 kg body weight.
Body-fat reference bands
Fitness reference: 14–<18% (men). Reference categories are not a diagnosis or a target.
Where to place the tape
Your fat and fat-free mass
Add an optional body weight to see mass estimates.
Fat-free mass includes muscle, bone, water and organs.
It is not the same as muscle mass.
These values inherit the uncertainty of the body-fat estimate.
Calculation & assumptions
Measurements are converted to inches before calculation.
BF% = 86.010 log₁₀(abdomen − neck) − 70.041 log₁₀(height) + 36.76
Example (your values)
170 cm height, 83 cm abdomen, 37 cm neck → 17.1% estimated body fat.
The female equation uses natural waist, hips and neck. Neither equation uses weight. No intermediate rounding.
An estimate for adults, not a direct body-composition measurement. Individual error can be meaningful. Not intended for children, pregnancy or situations where measurement landmarks are unreliable. Technical input limits do not establish clinical validity. This historical method is not a current official military assessment.
Frequently asked questions
How accurate is the Navy method?
It estimates body fat from circumferences rather than measuring it directly. Body shape, measurement technique and the population used to derive the equation affect accuracy. Use consistent landmarks for tracking; do not treat small changes as precise changes in body fat.
Why do women need a hip measurement?
The historical female equation includes natural waist plus hips minus neck. The male equation uses abdomen at the navel minus neck. These sex-specific equations use different coefficients.
Does weight change the percentage?
No. Optional weight only converts the estimated percentage into fat and fat-free mass. Leaving weight blank does not prevent a percentage calculation.
Is fat-free mass the same as muscle?
No. Fat-free mass includes water, bones, organs and muscle. This calculator cannot measure skeletal muscle mass.
Are these categories a diagnosis?
No. ACE reference categories are descriptive body-fat bands, not individualized health targets or a diagnosis. This estimate cannot replace a professional assessment.
Sources & References
Historical coefficients · 2013 appendix.
American Council on Exercise.
Academies
Historical Navy body-composition research.
References inform the calculation; no institutional endorsement. Source names identify the cited publications.
Understand your body composition. Go beyond the scale.