What is body fat percentage?
Body fat percentage is the fraction of your body weight that is fat tissue. It separates what BMI cannot: two 180 lb men at the same height can carry 12% or 30% body fat and look nothing alike. Athletic men sit around 6–13%, fit women around 14–21%.
How the calculator works
The U.S. Navy method uses log-transformed circumference measurements — height and neck for everyone, plus hips for women — and is the standard field test with roughly a 3–4% error band. The Deurenberg formula estimates body fat from BMI, age and sex when you do not have a tape measure handy; it is less personal but instant.
Common use cases
- Checking whether weight loss is coming from fat or muscle
- Setting a target weight for a fight, meet or season
- Tracking recomposition when the scale barely moves
Formula & measurement tips
Navy male formula: 495 / (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450, all in inches. Measure the waist at the navel, the neck below the larynx, keep the tape snug not tight, and measure twice — a half-inch slip moves the result by a full percentage point.
Frequently Asked Questions
How accurate is the Navy method?
About ±3–4% versus DEXA for most people. It trends well over time even when the absolute number is off.
Why do women need a hip measurement?
Female fat distribution concentrates at the hips; the female formula includes hip circumference to reflect that.
What body fat is visible abs?
For most men, around 10–12% and below; for women, 16–19% and below.
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