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Estimate body-fat percentage from a tape measure using the U.S. Navy circumference method. Free, no signup.
The U.S. Navy circumference method estimates body-fat percentage from tape measurements — neck and waist for men, plus hips for women — combined with height. It's free, repeatable, and accurate enough to track direction, which is what actually matters during a cut or a bulk.
Compared against DEXA scans, the Navy formula typically lands within ±3–4% for most physiques. It can under-read on lifters with well-developed necks and over-read on people who carry fat viscerally. The absolute number matters less than the trend: measure the same way, at the same time of day, every couple of weeks.
For context: essential fat is about 3–5% for men and 10–13% for women, and a fit, sustainable range is roughly 10–20% for men and 18–28% for women. Contest-lean levels below that are hard to hold and cost recovery and hormones.
Neck: just below the larynx, with the tape sloping slightly downward at the front. Waist: at the navel for men, at the narrowest point for women. Hips (women only): at the widest point. Keep the tape snug without compressing skin, and measure relaxed — not flexed or sucked in.
Roughly 10–20% for men and 18–28% for women spans the athletic-to-healthy range. Strength athletes usually perform best in the middle of those bands — extra leanness helps relative strength but very low body fat costs recovery, sleep, and hormone levels.
Every 2–4 weeks. Daily water and food shifts swamp real change; over a month, a consistent tape trend combined with average scale weight tells you clearly whether a cut is removing fat or muscle.
Want the number to actually go up? Snap My Gym builds percentage-based programs around your lifts and tracks them automatically. More evidence-first training articles on the blog.