Body Fat Calculator
Estimate your body fat percentage with a tape measure, using the US Navy method.
About this tool
Uses the US Navy circumference formulas, which estimate body fat from height and neck and waist measurements (plus hips for women). Categories follow the American Council on Exercise ranges. It is an estimate for adults, not a medical test.
Body fat percentage says more about health and fitness than weight alone, because it separates fat from muscle, bone and water. You do not need special scales: the US Navy method estimates body fat from a few tape-measure readings. Enter your height and your neck and waist measurements (and hips if you are a woman) to get an estimate, a category and, if you add your weight, your fat and lean mass.
How to use the Body Fat Calculator
- Choose your sex and whether you measure in centimetres or inches.
- Measure your neck just below the Adam’s apple and your waist at the navel, relaxed, not pulled in. Women also measure the hips at the widest point.
- Enter your height and the measurements, and your weight if you want fat and lean mass.
- Read your body fat percentage and category.
A man 178 cm tall
With a 38 cm neck and an 86 cm waist, the US Navy formula gives about 17.2% body fat, at the top of the fitness range for men (14 to 17%). At 80 kg that is about 13.8 kg of fat and 66.2 kg of lean mass. Losing 4 cm off the waist with the same neck would bring the estimate to about 14%.
How the US Navy method works
The method was developed by the US Navy to check fitness quickly without equipment. It uses the fact that fat is stored around the waist and hips, while the neck mostly reflects frame size, and combines them with height on a logarithmic scale. Studies find it is usually within a few percentage points of lab methods such as DEXA scans, but it can be off for very muscular people or people who carry fat differently. Measure at the same time of day, with the tape level and snug but not tight, and take each measurement twice. Typical ranges are about 14 to 24% for women in good health and 6 to 17% for fit men; essential fat is about 10 to 13% for women and 2 to 5% for men.
Frequently asked questions
How accurate is the US Navy body fat method?
For most adults it lands within about 3 to 4 percentage points of laboratory tests. Careful, repeated measurements make it more consistent, which is what matters for tracking change.
Why do women measure their hips?
Women tend to store more fat around the hips and thighs, so the female formula adds the hip measurement to give a fairer estimate.
What is a healthy body fat percentage?
Ranges vary with age, but for adults about 21 to 31% for women and 14 to 24% for men is common. Talk to a health professional about your own target.
Is body fat better than BMI?
They measure different things. BMI only uses weight and height; body fat estimates how much of that weight is fat, so it is more useful for muscular people.