What the result shows
Body fat percentage is the share of your weight that is fat. The rest is lean mass: muscle, bone, organs and water. Some fat is essential for health, so lower is not always better.
This calculator also shows fat mass and lean mass in kilograms or pounds, which makes changes easier to follow than a single percentage.
A worked example
A man is 180 cm tall with an 85 cm waist, a 38 cm neck and a weight of 80 kg. The Navy formula gives about 16.1% body fat, which falls in the fitness range. That is about 12.9 kg of fat and 67.1 kg of lean mass.
If his waist grew to 100 cm with everything else the same, the estimate would rise to about 24%. Waist changes dominate the result, so measure carefully.
Using it well
Measure at the same time of day, under the same conditions, every few weeks. Trends matter more than any single reading. Do not use the result to set extreme goals.
People who are very muscular, older, pregnant or have medical conditions may get misleading estimates. Speak to a doctor or dietitian for personal advice.
Notes
This tool is for general information and is not a medical diagnosis. The calculation uses centimetres internally, and inches are converted automatically.
Questions people ask
How does the US Navy body fat method work?
It estimates body fat from circumference measurements and height, using a formula developed from military studies. Men use waist and neck. Women also use hip. A bigger waist relative to height and neck suggests more body fat.
How accurate is it?
It is an estimate and can be off by several percentage points, depending on body shape and measurement technique. It is useful for tracking change over time, but scans such as DEXA are more accurate.
How do I measure correctly?
Stand relaxed and measure on bare skin. Measure the waist at the navel, the neck just below the larynx, and the hip at the widest point. Keep the tape level and snug without squeezing. Take each measurement twice and average.
What is a healthy body fat percentage?
Ranges differ by sex, age and goals. Commonly cited ranges, such as those from the American Council on Exercise, put average at about 18–24% for men and 25–31% for women. A doctor can advise what is right for you.
Is body fat better than BMI?
They measure different things. BMI uses only height and weight, so it cannot tell muscle from fat. Body fat estimates are often more informative for fit or very muscular people, but both are screening tools, not diagnoses.