Know your body fatand how wrong the number could be.
Every body-fat calculator is guessing. Most hide it behind one confident number. This one shows you the estimate, its real margin of error, and three methods side by side, so you can track the trend you can trust instead of chasing a false decimal.
US Navy circumference method. Most accurate of the three.
How a body fat calculator works
A body fat calculator estimates the percentage of your weight that is fat rather than muscle, bone, and water. It cannot see inside you, so it infers body fat from measurements that correlate with it: the circumference of your neck, waist, and hips for the US Navy method, your height and weight for the BMI method, or the thickness of a pinched skinfold for the caliper method.
Because every method is an estimate, the honest output is a range. The US Navy tape method, the most reliable of the three for home use, typically lands within 3 to 4 percentage points of a clinical DEXA scan. This tool runs all three methods at once so you can triangulate, and it shows the margin of error instead of hiding it behind a single confident-looking decimal. Measure the same way each month and the trend it reveals is far more useful than any single reading.
Common questions
How do you measure body fat at home?
The most reliable at-home method is the US Navy tape test: measure your neck and waist (plus hips for women) with a soft tape, then run those numbers through the Navy formula. It needs no special equipment, takes about two minutes, and lands within roughly 3 to 4 percentage points of a clinical scan for most people. Calipers (pinching a skinfold) can be slightly more accurate if you measure the same spots consistently, and a BMI-based estimate works when you have no tape at all but is the least precise.
How accurate is the US Navy body fat method?
The US Navy circumference method is accurate to within about 3 to 4 percentage points of a DEXA or hydrostatic reading for most adults, which is why this tool shows your result as a range, not a single number. It tends to overestimate body fat for very muscular people with thick necks and underestimate it for lean people with narrow waists. Use it to track change over weeks and months rather than as an exact figure on any one day.
What is a healthy body fat percentage?
A healthy body fat percentage is roughly 10 to 20 percent for men and 18 to 28 percent for women, with athletes often sitting lower and essential-fat floors of about 2 to 5 percent for men and 10 to 13 percent for women. These are general fitness-reference ranges, not diagnostic cutoffs. Where you fall ideally depends on age, training, and health markers your clinician can interpret alongside the number.
Is a body fat calculator as accurate as a DEXA scan?
No. A body fat calculator estimates from tape measurements or BMI, while a DEXA scan directly measures fat, lean mass, and bone with an error of about 1 to 2 percent. A calculator's typical error is 3 to 4 percentage points or more. The calculator's real strength is consistency and zero cost: measured the same way each time, it tracks your trend reliably even though the absolute number is an estimate.
How do you lower your body fat percentage?
You lower body fat percentage by holding a modest calorie deficit, eating enough protein (roughly 0.7 to 1 gram per pound of body weight) to protect muscle, and training with resistance so the weight you lose is fat rather than lean mass. Sleep, stress, and hormones also set the ceiling on how fast it moves. If the number stalls for months despite consistent effort, that plateau can be worth reviewing with a clinician rather than guessing.