U.S. Navy method (Hodgdon & Beckett) — the more widely used tape estimate.
Body fat—
Category—
Fat mass—
Lean mass—
Estimate your body fat percentage from tape-measure girths (the U.S. Navy or U.S. Army method) or from your BMI. Everything runs in your browser — nothing is uploaded.
How to measure body fat with a tape
The U.S. Navy method estimates body fat from a few girth measurements and your height, using a formula developed by the Navy (Hodgdon & Beckett) as a field-friendly alternative to skinfold calipers or a DEXA scan. Stand relaxed and use a flexible tape, snug against the skin but not compressing it. Measure your neck just below the larynx (Adam's apple), sloping slightly downward at the front. Measure your waist at the navel for men, or at the narrowest point of the torso for women. Women also measure hips at the widest point around the buttocks — the men's formula does not use hips, which is why that field hides when Sex is set to Male. Enter your height, and the calculator applies the Navy formula automatically as you type.
The U.S. Army method
The U.S. Army tab uses the same neck, waist and height measurements but a different equation — the circumference formula from Army Regulation 600-9, which the Army uses for its own body-composition standard. It takes the same girths and returns a slightly different percentage, usually within a point or two of the Navy figure, so switching between the two tabs is a quick way to see the spread. Neither is a lab measurement; both are field estimates meant to track change over time rather than give a single exact number. If you are checking yourself against the Army standard, remember the service also applies age-based maximum limits that this calculator does not enforce.
Body fat vs BMI
BMI compares your weight to the square of your height and doesn't distinguish muscle from fat, so a muscular person and a person carrying extra fat can land on the same BMI. Body-fat percentage instead estimates what fraction of your weight is actually fat versus lean tissue (muscle, bone, organs and water), which is why it's a better read on body composition. If you want your BMI value itself — the figure this calculator's BMI method is built on — use the BMI Calculator. For just how far the two can drift apart, see why one BMI hides a 22-point body-fat gap.
Healthy body fat ranges
Using the American Council on Exercise categories that this calculator's results are tinted by: for men, essential fat is roughly 2 to 5%, athletes 6 to 13%, fitness 14 to 17%, average (acceptable) 18 to 24%, and 25% or higher is classed obese. For women, essential fat is roughly 10 to 13%, athletes 14 to 20%, fitness 21 to 24%, average (acceptable) 25 to 31%, and 32% or higher is classed obese. Women carry more essential fat than men by design, which is why the ranges differ by sex rather than sharing one scale.
Frequently Asked Questions
How accurate is the Navy body fat method?
The U.S. Navy body fat method typically comes within about 3 to 4 percentage points of a DEXA scan for most people, which is good enough to track progress over time. Accuracy depends on measuring the same way each time — a snug but not tight tape, at the same spots, without pulling the tape in.
Should I use the tape method or the BMI method?
Use the tape (Navy or Army) method if you can measure your neck and waist accurately — it looks at actual body girths, so it is the more reliable of the two. The BMI method is a fallback for when you only have your height and weight, since BMI on its own cannot tell muscle from fat, and the Deurenberg formula behind it will overstate body fat on a muscular build. Neither is a lab measurement: tape estimates typically sit within about three to four percentage points of a DEXA scan, and a centimetre of tape error at the waist can move the answer by a full point. Measure at the same time of day, ideally before eating, and watch the trend across several weeks rather than any single reading.
What is the difference between the Navy and Army body fat methods?
Both estimate body fat from the same neck, waist and height measurements (plus hips for women), but they use different formulas. The Navy uses the Hodgdon-Beckett equation; the Army uses the circumference formula from Regulation 600-9. For the same measurements they usually land within a point or two of each other. The Army also applies age-based maximum body-fat limits for its standard, which this calculator does not enforce.
Why does the calculator ask for hips only for women?
The Navy formula for women includes a hip measurement because female fat distribution is not captured accurately by neck and waist alone. The men's formula only needs neck, waist and height, so the hips field is hidden when Sex is set to Male. Measure the hips at the widest point around the buttocks, with the tape level all the way round and snug but not compressing. The waist site also differs by sex on this page: at the navel for men, at the narrowest point of the torso for women.
What is a healthy body fat percentage?
Using the American Council on Exercise ranges, a healthy or acceptable body fat percentage is roughly 18 to 24 percent for men and 25 to 31 percent for women, with lower ranges for athletes and higher ranges falling into the obese category. Essential fat — the minimum the body needs for normal hormonal and organ function — is about 2 to 5 percent for men and 10 to 13 percent for women, so a very low reading is not a goal in itself. Healthy ranges shift with age and individual body type, so treat this as a general guide rather than a target. The calculator also converts your percentage into fat mass and lean mass, which is usually the more useful pair of numbers to track while dieting, because holding lean mass steady while fat mass falls is the outcome you want.