# Difference between Body Mass and Body Weight

##### Key Difference: Mass is the amount of “matter” that an object has. Whereas, weight is the effect that the gravitational pull has on the mass of the object. While this distinction should apply to Body Mass and Body Weight, in reality, Body Weight might refer to the body’s weight or the body’s mass. In order to understand the difference between Body Mass and Body Weight, one must first understand the difference between Mass and Weight. In physics, mass is the amount of “matter” that an object has. Whereas, weight is the effect that the gravitational pull has on the mass of the object. For example, an object will have the same mass on Earth and the same mass on the Moon, but it will weight less on the Moon, than on Earth as the Moon has a lower gravitational pull than the Earth.

While this distinction should apply to Body Mass and Body Weight, in reality, Body Weight might refer to the body’s weight or the body’s mass. This is due to the fact that in practicality the body’s mass and weight would be the same, as it is unlikely that people would actually weight the body on celestial objects other than Earth.

Ideally, however, body weight refers to the person’s weight. As person’s weight will differ if the gravitational force acting on a body changes. The difference here is the fact that while in physics, the weight would be measured in newtons (Newton is unit of force. Force = Mass x acceleration). However, weight is commonly measured in kilograms. Some countries, such as the United States of America, used pounds (lbs). Kilograms and pounds are actually units of measurement for mass, not weight.

Body weight is usually measured wearing clothes, but without any other objects on the body. This includes shoes, mobile phones, wallets, etc. Weight is often used to indicate the general health and well being of a person. In order to help with this, there is also something called the Body Mass Index (BMI). This index a measure of relative weight measured according to the person’s weight and height. BMI is a weight-for-height ratio that is calculated by dividing the body mass in kilogram by the height in meters squared (BMI = mass (kg) / (height (m))2).

The BMI is used to figure out whether a person falls under the normal weight, underweight or overweight ranges for their height. However, the BMI has received a lot of criticism, especially regarding where the categories for overweight and obese should be set. There have also been numerous other perceived limitations and problems with the BMI.

Comparison between Body Mass and Body Weight:

 Body Mass Body Weight Definition Mass is the amount of matter that makes up a body. Weight is the measurement of the gravitational force acting on a body. Change Mass does not change according to location. Weight increases or decreases with higher or lower gravity. Zero Mass can never be zero. Weight can be zero if no gravity acts upon an object, as in space.

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