How to use the body fat calculator
Select your sex and enter your height, neck, and waist measurements in centimetres — plus hips if you are female. Optionally add your weight to also see your fat mass and lean mass. The calculator applies the U.S. Navy formula and shows your estimated body fat percentage and category instantly, all in your browser.
Why body fat beats the scale alone
Your bodyweight lumps muscle, fat, bone, and water into one number, so it cannot tell you whether a change is fat lost or muscle gained. Body fat percentage separates the part most people actually want to track. Two people at the same weight and height can look and perform very differently depending on their body composition, which is exactly what this measure captures.
Measure consistently to track progress
The single most important habit is to measure the same way every time: same tape tension, same spots, same time of day. Because the Navy method depends on circumferences, a centimetre of difference in how you hold the tape can shift the result by a percentage point or two. Treat any one reading as an estimate, but a series of readings taken consistently gives a reliable picture of the trend. This tool is for general information and is not a medical assessment.