Body Fat % (US Navy Method)
Estimate body fat percentage using the US Navy circumference method (Hodgdon & Beckett, 1984), validated against hydrostatic weighing.
Results
What is it?
This calculator estimates body fat percentage using the US Navy circumference method developed by Hodgdon & Beckett (1984). It uses simple tape-measure readings of waist, neck, and hip circumferences and has been validated against hydrostatic (underwater) weighing.
How to use
Select your biological sex, then enter height, waist circumference (at navel), neck circumference, and hip circumference (females only — males may enter 0 for hip). The formula uses logarithmic equations calibrated separately for each sex.
Example scenario
A male with height 175 cm, waist 85 cm, neck 38 cm: BF% = 86.01 × log₁₀(85 − 38) − 70.04 × log₁₀(175) + 36.76 ≈ 18.6%. This falls within the "fitness" category for adult males.
Pro tip
Measure waist at the navel and neck at the narrowest point for consistency. Take all measurements on bare skin, not over clothing, and measure three times to average out variation. This method is most accurate for body fat ranges of 10–35%.