Health & Fitness · Body Metrics
Formula verified
Body Fat Percentage Calculator
Enter your waist, neck and height (and hip, if female) to estimate body fat percentage using the U.S. Navy circumference method — no scale required.
Units
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Estimated body fat
19.4%
Average
Category
Average
Method
U.S. Navy
Step-by-step proofCheck by hand
This is a circumference-based estimate, not a body-composition scan. The U.S. Navy method is accurate to within a few percentage points for most people but can be less reliable for very lean athletes or people with an atypical body shape. For a precise measurement, ask a professional about DEXA, hydrostatic weighing, or skinfold calipers.
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How the U.S. Navy method works
The method estimates body fat from a handful of tape-measure circumferences instead of a scan. For men it uses waist and neck; for women, since fat distribution differs, it adds hip and drops the direct waist-minus-neck relationship. Both use a log-based formula, since body fat percentage doesn't scale in a straight line with circumference.
The formulas
Male: 86.010×log₁₀(waist−neck) − 70.041×log₁₀(height) + 36.76
Female: 163.205×log₁₀(waist+hip−neck) − 97.684×log₁₀(height) − 78.387
Worked example
A man 70 in tall with a 35 in waist and 15 in neck: 86.010×log₁₀(35−15) − 70.041×log₁₀(70) + 36.76 ≈ 19.4% body fat — in the "Average" category.
Frequently asked questions
Where does the U.S. Navy method come from?
It was developed by Hodgdon and Beckett at the Naval Health Research Center in 1984 as a fast, no-equipment way to estimate body fat from a tape measure, and it's still the method all four U.S. armed services use for body-composition standards today.
Why does the formula need a neck measurement?
The neck measurement acts as a rough baseline for frame size, so the waist (and, for women, hip) measurement can be read as fat above that baseline rather than in absolute terms — it's part of what lets a tape measure alone stand in for a scan.
What do the body fat categories mean?
The ranges shown come from the American Council on Exercise's published categories — essential fat, athletes, fitness, average, and obese — and describe typical ranges for each group rather than a target everyone should aim for. What's healthy varies by age, sex and individual circumstances.
Sources and method
- Hodgdon, J.A. & Beckett, M.B. (1984), Naval Health Research Center — U.S. Navy circumference method.
- American Council on Exercise — published body fat percentage categories.