What is the term for the percentage of your body weight that is made up of fat?

The percentage of your body weight made up of fat is called body fat percentage.

Body fat percentage compares the total mass of fat in the body with total body mass, then expresses the result as a percentage. It includes essential fat, which supports normal functions such as hormone production and organ protection, as well as stored fat in adipose tissue.

This measure differs from BMI, which uses height and weight to classify weight categories but does not directly distinguish fat from muscle, bone, or water. Two people with the same BMI can therefore have noticeably different body fat percentages.

Body fat percentage can be estimated in several ways, including skinfold calipers, bioelectrical impedance scales, air-displacement testing, and dual-energy X-ray absorptiometry. These methods do not always produce identical results, because hydration, equipment, body-fat distribution, and measurement technique can affect estimates.

The number is useful for describing body composition, but it should be interpreted alongside health, fitness, age, and other measurements rather than treated as a complete diagnosis.