Body Fat Calculator
Estimate your body-fat percentage with just a tape measure — the U.S. Navy circumference method. No calipers, no scale gimmicks.
Tape estimates carry a margin of about ±3–4% versus DEXA — useful for tracking change over time, not a medical measurement. Measure relaxed (don't suck in), same time of day each check. Not medical advice.
How the Navy body-fat method works
The U.S. Navy circumference method estimates body fat from a few tape measurements — height, neck, and waist (plus hips for women). It was built to screen large groups quickly, and decades of use show it tracks reasonably well against lab methods for most body types. It won't match a DEXA scan to the decimal, but it's free, repeatable, and perfect for tracking direction over time: measure every 2–4 weeks, same conditions, and watch the trend rather than any single reading.
If your goal is changing that number, the levers are unglamorous: a sensible calorie target, enough protein to hold muscle (use our protein calculator), progressive resistance training, and sleep. Supplements support the plan — they aren't the plan.
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Frequently Asked Questions
How accurate is the tape-measure body fat method?
Expect roughly ±3–4% versus a DEXA scan. It's most useful for tracking change over time under consistent conditions, not for pinpoint accuracy on any single day.
What is a healthy body fat percentage?
Commonly cited fitness ranges are about 14–17% for men and 21–24% for women, with athletes often lower. Healthy varies by individual — talk to your healthcare provider about what's right for you.
How often should I measure?
Every 2–4 weeks is plenty. Measure at the same time of day, relaxed, before eating if possible. Day-to-day fluctuations are mostly water and food volume, not fat.