Last updated: October 2026
How does the Navy body fat calculator work?
Short answer: the U.S. Navy method estimates body fat % from tape measurements — height, neck and waist for men, plus hip for women. Enter your numbers above for an instant result with category, BMI and fat vs lean mass.
How accurate is it?
Within about 3–4% of DEXA scans for most people — good enough to track trends month to month. It's less accurate for very muscular or very lean people, since a tape can't distinguish muscle from fat the way a scan can. Measure consistently (same time of day, relaxed, tape horizontal) and watch the trend, not a single number.
Where to measure
Waist: at the navel, tape horizontal, relaxed — don't suck in. Neck: just below the Adam's apple. Hip (women): at the widest point. Keep the tape snug but not compressing the skin.
Frequently asked questions
How does the Navy body fat calculator work?
It uses the U.S. Navy's circumference method: for men, body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76; for women it adds the hip measurement. Measure with a tape in inches or centimeters and enter the values above.
How accurate is the Navy body fat method?
Within about 3-4% of DEXA scans for most people — good for tracking trends over time. It's less accurate for very muscular or very lean individuals, since it can't distinguish muscle from fat the way a scan can.
Where do you measure waist for body fat?
At the navel (belly button), horizontal around the abdomen, relaxed — don't suck in. Measure the neck just below the Adam's apple, and hips at the widest point for women.
What is a healthy body fat percentage?
For men: 14-17% is fitness level, 18-24% average, 25%+ obese. For women: 21-24% fitness, 25-31% average, 32%+ obese. Athletes run lower: 6-13% men, 14-20% women.
Is body fat percentage better than BMI?
Yes for most people — BMI can't tell muscle from fat, so muscular people score as 'overweight'. Body fat % measures what actually matters. The calculator shows both so you can compare.