TOOLS / BODY FAT
Body Fat Percentage Calculator (Navy Method)
Estimate body fat percentage from neck and waist tape measurements using the U.S. Navy method, with the typical margin of error and reference bands.
A tape measure, and a ballpark.
These are research-based estimation formulas, and results vary by individual. They are not a substitute for medical judgment — consult a doctor if you have a medical condition.
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If entered, this value is passed along to the "Calculate FFMI with this value" link.
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Formula & Sources
The U.S. Navy Method estimates body fat percentage from tape-measure circumferences of the neck and waist (plus hip for women). Developed in the 1980s as a U.S. Navy body-composition standard, it remains widely used for its simplicity.
Formula for men
Body fat % = 495 / (1.0324 − 0.19077×log10(waist − neck) + 0.15456×log10(height)) − 450
Formula for women
Body fat % = 495 / (1.29579 − 0.35004×log10(waist + hip − neck) + 0.22100×log10(height)) − 450
For the log10 term to stay positive, the formula requires waist to exceed neck (men), or waist plus hip to exceed neck (women). The calculation cannot proceed if this condition isn't met.
Supporting research
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Reviewed by
Tomonobu SomedaHead Trainer at well-being-life Gym
What research shows, and what happens on the gym floor — I check our content against both.
Content reviewed from the perspective of coaching practice and supplement-industry experience
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