Body Fat Calculator: U.S. Navy Method and BMI Estimate
Free body fat calculator: estimate your body fat percentage with the U.S. Navy tape-measure method (neck, waist, hips) or the BMI method. See your category, fat and lean mass, set a body-fat goal, and send the result to the BMR calculator.
Tape measurements (for the U.S. Navy method, the most accurate of the quick ones): measure bare skin, relaxed, to the nearest half cm / quarter inch. Skip them to get the BMI-based estimate only.
Where you are
Set a body-fat goal
Assumes you keep all your muscle and lose only fat, which is the best case; most people lose a little of both.
Compare the methods
Tape and formula methods are typically within 3–4 percentage points of a DEXA scan for an average person, and less accurate at the extremes (very lean, very muscular or very heavy).
How this body fat calculator works
Body fat percentage is the share of your weight that is fat. It tells you more than BMI, because it separates fat from muscle, bone and water. This calculator gives two estimates:
- U.S. Navy method (tape measure): uses height, neck and waist (plus hips for women). Men: 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women: 495 ÷ (1.29579 − 0.35004 × log10(waist + hips − neck) + 0.22100 × log10(height)) − 450, with measurements in cm.
- BMI method (Deurenberg, 1991): 1.20 × BMI + 0.23 × age − 10.8 × (1 for men, 0 for women) − 5.4. It needs no tape, but it assumes an average build, so it overestimates in muscular people.
Body fat percentage categories
Ranges from the American Council on Exercise. Essential fat is the minimum your body needs to function; staying near or below it is unhealthy. Healthy ranges also rise somewhat with age.
How to measure properly
- Neck: just below the larynx (Adam's apple), sloping slightly down at the front, tape snug but not squeezing.
- Waist: men at the navel; women at the narrowest point (or the navel if there is no obvious narrowing). Relax and breathe out; do not suck in.
- Hips (women): the widest point of the buttocks, feet together.
- Measure three times and use the average. Measure at the same time of day (mornings are most consistent).
Questions
- What is a good body fat percentage?
- For general health, roughly 10–20% for men and 18–28% for women is a common target, with athletes lower. See the table above.
- Is this as accurate as a DEXA scan or calipers?
- No. A DEXA scan, hydrostatic weighing or a good caliper reading from a trained person is more accurate. The tape method is good for tracking change over time with the same technique.
- Why do my two estimates differ?
- The BMI method cannot tell muscle from fat, so it reads high for muscular people and low for people who carry little muscle. Trust the tape method more, and look at the trend.
- Is my data private?
- Yes. Everything stays in your browser. Nothing is uploaded unless you copy a link and share it yourself.
Related: BMR Calculator (use your body-fat % for the Katch-McArdle equation) · BMI Calculator