Estimate body fat percentage using the U.S. Navy circumference method — just a tape measure required.
What it means
Developed in 1984 for U.S. Navy body composition assessments, this formula uses circumference measurements and height to fit a log-based equation. It's within ~3% of DEXA scans for most body types — better than calipers in inexperienced hands.
Measure in the morning, before eating, with a flexible tape. Don't pull tight or leave slack. Take each measurement twice and average — a quarter-inch error on the waist can swing the result by 1–2%.
FAQ
Yes, especially for muscular or lean people. BMI treats a 200-lb lifter and a 200-lb couch potato the same. Body fat % gets at the actual composition.
Roughly: men 10–20%, women 18–28%. Athletes run lower; "essential fat" floors are ~3% for men and ~10% for women. Single-digit body fat is not a sustainable everyday target.
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