Body Fat % Calculator
Estimate body fat percentage using the U.S. Navy circumference method. Fast, free, and fully client-side.
Calculator Inputs
How the Body Fat % Calculator Works
Estimates body fat percentage using the U.S. Navy circumference method — a non-invasive formula developed for military body composition screening, using neck, waist (and hip for women), and height measurements. A circumference-based estimate, not as precise as DEXA or hydrostatic weighing — useful for tracking trends over time, not a medical diagnosis.
Formula
Men: 495 / (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450 · Women: 495 / (1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450
Developed by the U.S. Navy as a fast, equipment-free body composition estimate from tape-measure circumferences. All measurements in inches.
Calculation Example
A man with a 34" waist, 15" neck, and 70" height: log₁₀(34−15)=1.279, log₁₀(70)=1.845 → roughly 12% body fat.
Frequently Asked Questions
How accurate is the Navy method?
It typically estimates within 3-4% of more precise methods like DEXA scans for most body types, but can be less accurate for very lean or very muscular individuals.
Why does the formula differ for men and women?
Body fat distribution patterns differ by sex, so the Navy method uses separate calibrated formulas — women additionally measure hip circumference.
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