Body Weight

The term body weight is used colloquially and in the biological and medical sciences to refer to a person's mass or weight. Body weight is measured in kilograms, a measure of mass, throughout the world, although in some countries such as the United States and Canada it is measured in pounds, or as in the United Kingdom, stones and pounds. Most hospitals, even in the United States, now use kilograms for calculations, but use kilograms and pounds together for other purposes. Strictly speaking, the body weight is the weight of the person without any items on, but practically body weight is taken with clothes on but often without the shoes and heavy accessories like mobile phones and wallets.

While the terms mass and weight are often used interchangeably in the context of body weight, they actually refer to separate but related concepts in physics. Mass is a measure of an object's inertia and is independent of the effects of gravity, while weight is a measure of the force due to gravity. Thus, if a person were to travel from Earth to the Moon, where there is less gravity, their mass would remain unchanged but their weight would decrease.