Body fat calculator (US Navy method)
It uses the Hodgdon and Beckett equations adopted by the US Navy and splits your weight into fat and lean mass if you enter it.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter sex, height, neck, waist, hip (women) and weight (optional).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Men: fat % = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women: 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450. All in cm.
Example
Inputs: Sex = Male, Height = 178 cm, Neck = 38 cm, Waist = 85 cm, Hip (women) = 100 cm. Result: Body fat: 16.4%; Fat mass: 13.1 kg; Lean mass: 66.9 kg.
Limits and caveats
- A tape estimate can differ from a DEXA scan by about 3 to 4 percentage points.
- Measure the waist at the navel for men and at the narrowest point for women, and the neck just below the larynx.
Questions about this tool
What is a normal body fat percentage?
The ACE chart puts average adults at roughly 14 to 24% for men and 21 to 31% for women.
Why do women need a hip measurement?
Women tend to store more fat around the hips, so the formula adds it for a better estimate.
How accurate is this method?
It is a good home estimate. Measuring the same way each time matters most for tracking change.