# What Is the Difference Between Weight and Mass?

## Mass vs Weight: Comparing and Understanding the Differences

The terms "mass" and "weight" are used interchangeably in ordinary conversation, but the two words don't mean the same thing. The difference between mass and weight is that mass is the amount of matter in a material, while weight is a measure of how the force of gravity acts upon that mass.

• Mass is the measure of the amount of matter in a body. Mass is denoted using m or M.
• Weight is the measure of the amount of force acting on a mass due to the acceleration due to gravity. Weight usually is denoted by W. Weight is mass multiplied by the acceleration of gravity (g).

### ﻿ $W = m * g$﻿Comparing Mass and Weight

For the most part, when comparing mass and weight on Earth—without moving!—the values for mass and weight are the same. If you change your location with respect to gravity, mass will remain unchanged, but weight will not. For example, your body's mass is a set value, but your weight is different on the Moon compared with on Earth.

## How Much Do You Weigh on Other Planets?

While a person's mass doesn't change elsewhere in the solar system, the acceleration due to gravity and weight varies dramatically. The calculation of gravity on other bodies, as on Earth, depends not just on mass but also on how far the "surface" is from the center of gravity. On Earth, for example, your weight is slightly lower on a mountain top than at sea level. The effect becomes even more dramatic for large bodies, such as Jupiter. While the gravity exerted by Jupiter due to its mass is 316 times greater than that of Earth, you wouldn't weigh 316 times more because its "surface" (or the cloud level we call the surface) is so far out from the center.

Other celestial bodies have different values of gravity than Earth does. To get your weight, simply multiply by the appropriate number. For example, a 150-pound person would weigh 396 pounds on Jupiter, or 2.64 times their weight on Earth.

You may be surprised by your weight on other planets. It makes sense that a person would weigh about the same on Venus, because that planet is about the same size and mass as Earth. However, it may seem odd that you'd actually weigh less on the gas giant Uranus. Your weight would be only slightly higher on Saturn or Neptune. Although Mercury is much smaller than Mars, your weight would be about the same. The Sun is much more massive than any other body, yet you'd "only" weigh about 28 times more. Of course, you'd die on the Sun from the massive heat and other radiation, but even if it were cold, the intense gravity on a planet that size would be deadly.

## Resources and Further Reading

• Galili, Igal. “Weight versus Gravitational Force: Historical and Educational Perspectives.” International Journal of Science Education, vol. 23, no. 10, 2001, pp. 1073-1093.
• Gat, Uri. “The Weight of Mass and the Mess of Weight.” Standardization of Technical Terminology: Principles and Practice, edited by Richard Alan Strehlow, vol. 2, ASTM, 1988, pp. 45-48.
• Hodgman, Charles D., editor. Handbook of Chemistry and Physics. 44th ed., Chemical Rubber Co, 1961, pp. 3480-3485.​
• Knight, Randall Dewey. Physics for Scientists and Engineers: a Strategic Approach. Pearson, 2004, pp 100-101.
• Morrison, Richard C. “Weight and Gravity—The Need for Consistent Definitions.” The Physics Teacher, vol. 37, no. 1, 1999.
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Helmenstine, Anne Marie, Ph.D. "What Is the Difference Between Weight and Mass?" ThoughtCo, Aug. 25, 2020, thoughtco.com/mass-and-weight-differences-606116. Helmenstine, Anne Marie, Ph.D. (2020, August 25). What Is the Difference Between Weight and Mass? Retrieved from https://www.thoughtco.com/mass-and-weight-differences-606116 Helmenstine, Anne Marie, Ph.D. "What Is the Difference Between Weight and Mass?" ThoughtCo. https://www.thoughtco.com/mass-and-weight-differences-606116 (accessed September 23, 2021).