Body Fat Calculator
Body Fat Calculator
Estimate body fat from tape measurements.
How it works
The historical Navy circumference method estimates body fat from a small number of tape measurements. It is a population-based model, not a direct scan.
Using this calculator
Measure on bare skin with a level, snug tape without compressing it. For the male equation, measure the abdomen at the navel. For the female equation, measure the natural waist and the widest part of the hips. Measure the neck below the larynx. Use consistent technique.
Male: 86.010 × log₁₀(abdomen − neck) − 70.041 × log₁₀(height) + 36.76
Female: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
What to keep in mind
Body shape and tape placement can change the estimate substantially. Very low or high outputs are rejected for remeasurement. No body-fat “ideal” or medical diagnosis is assigned.
Sources & further reading
Hodgdon and Beckett method · Research and limitations ↗Frequently asked questions
Why do repeat measurements differ?
A shifted tape, different posture or tape tension can affect the inputs. Small changes in an estimate are not proof of a real body-composition change.
Are my entries saved?
No. Calculator inputs remain in the current page and are cleared when you reload or leave. The tools do not upload your entries.
Why are results rounded?
The display is rounded for readability. Calculations use unrounded intermediate values. An estimate should not be interpreted as an exact measurement.