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Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.
Health
Generated on May 23, 2026
Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.
This body-fat calculator uses the US Navy tape-measure method to estimate body-fat percentage from your height, neck, and waist (plus hip for women). Originally developed in 1984 by Hodgdon and Beckett for the US military's fitness standards, it is a no-cost alternative to expensive DEXA scans or skinfold calipers. With careful measurement under good conditions, accuracy is within roughly ±3% of laboratory methods — more than adequate for tracking trends over time, setting realistic fitness goals, and monitoring body-composition progress during a diet or training cycle.
Formula
Men: BFP = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women: similar with waist + hip − neck. All measurements in centimeters.BMI told you you're 'normal' but you can still pinch a soft layer around your waist and you're wondering what's actually going on. The honest answer is: BMI can't see fat. It sees mass. Two people at the same height and weight can be wildly different — one 18 percent body fat with visible muscle, the other 32 percent body fat with almost none. The US Navy tape-measure method this calculator uses was originally built in 1984 for the American military's fitness standards and lands within plus or minus 3 percent of a DEXA scan when you measure carefully. Carefully matters: neck just below the Adam's apple, waist at its narrowest point above the navel, hip at the widest point around the buttocks. Same time of day, same posture, every measurement. The phrase 'skinny-fat' exists for a reason — a slim-looking person with low muscle and high body fat is still at metabolic risk, and BMI completely misses it. The cleanest target most people should aim for is 14 to 17 percent body fat for men or 21 to 24 percent for women, where you start seeing real muscle definition without going into hormone-disrupting territory. Track monthly, not weekly — daily readings are mostly water noise. And remember: very low body fat is not healthy. Below 5 percent for men or 13 percent for women, the body starts shutting things down — hormones drop, periods stop, recovery slows. Lean is the goal, not skeletal.
This body-fat calculator uses the US Navy tape-measure method to estimate body-fat percentage from your height, neck, and waist (plus hip for women). Originally developed in 1984 by Hodgdon and Beckett for the US military's fitness standards, it is a no-cost alternative to expensive DEXA scans or skinfold calipers. With careful measurement under good conditions, accuracy is within roughly ±3% of laboratory methods — more than adequate for tracking trends over time, setting realistic fitness goals, and monitoring body-composition progress during a diet or training cycle.
The US Navy formula derives body density from specific body-circumference measurements (waist − neck for men; waist + hip − neck for women) using logarithmic functions. Density is then converted into fat percentage via the Siri equation (495/density − 450), which is a standard body-composition conversion. All inputs must be in centimeters for the formula to work correctly; the calculator handles conversion automatically if you enter inches.
American Council on Exercise body-fat percentage ranges for men and women by fitness level.
| Category | Men (%) | Women (%) | Notes |
|---|---|---|---|
| Essential Fat | 2–5 | 10–13 | Minimum for health — hormonal, organ function |
| Athletes | 6–13 | 14–20 | Competitive bodybuilder / elite athlete range |
| Fitness | 14–17 | 21–24 | Visible muscle definition, lean physique |
| Average | 18–24 | 25–31 | Typical healthy adult; no visible muscle definition |
| Obese | 25+ | 32+ | Health risks rise; weight management recommended |
An athletic man at 10% body fat shows clear abdominal separation; a woman at 18% shows similar definition.
Essential-fat minimums (2–5% men / 10–13% women) are biological limits — below these, hormones fail.
Average North American / European adult: ~22% men, ~32% women — up from ~15% / 27% in 1960.
BMI and body fat % can diverge sharply: a muscular man at 80 kg with BMI 26 ('overweight') may actually be 12% body fat ('athletic').
A man at 180 cm with neck 40 cm and waist 85 cm has approximately 15% body fat — the 'Fitness' category for men.
A woman at 165 cm with neck 32 cm, waist 75 cm, and hip 95 cm has about 24% body fat — 'Fitness' for women.
A man at 175 cm with neck 42 cm and waist 100 cm has around 25% body fat — borderline high, 'Average' category.
A male athlete at 185 cm with neck 41 cm and waist 80 cm measures about 10% body fat — the 'Athlete' category.
A woman at 170 cm with neck 33 cm, waist 85 cm, and hip 100 cm has roughly 29% body fat — 'Average' category.
A man at 170 cm with neck 38 cm and waist 78 cm measures around 13% body fat — firmly within the 'Athlete' range, typical of lean recreational athletes.
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