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Mass vs. Density: What's the Difference?

Edited by Janet White || By Harlon Moss || Published on November 25, 2023
Mass is the amount of matter in an object, while density is the mass per unit volume of an object.

Key Differences

Mass refers to the amount of matter contained within an object or substance. On the other hand, density conveys how tightly that matter is packed together within a specific volume.
While mass remains consistent regardless of location (e.g., on Earth or on the Moon), density can change based on conditions, such as temperature or pressure.
Mass is typically measured in kilograms (kg) or grams (g), depending on the context. In contrast, density is expressed as mass per unit volume, usually in units like kilograms per cubic meter (kg/m^3) or grams per cubic centimeter (g/cm^3).
An object's mass gives insight into the total amount of atoms and molecules present. Density, however, provides information about how these atoms and molecules are distributed in space.
Mass is an intrinsic property of matter and doesn't vary with size. Density might change if the arrangement or compactness of particles within an object changes, even if the mass remains the same.

Comparison Chart


Amount of matter in an object.
Mass per unit volume of an object.

Measurement Units

Typically measured in kilograms or grams.
Often measured in kg/m^3 or g/cm^3.

Changes Based on Location

Remains consistent regardless of location.
Can change with conditions like temperature or pressure.

Relation to Volume

Independent of volume.
Directly related to volume.


Intrinsic property of matter.
Reflects compactness or arrangement of particles.

Mass and Density Definitions


A property of matter that doesn't change based on location.
The mass of a rock remains the same whether it's on Earth or the Moon.


Mass divided by volume for a substance.
The density of water is 1 gram per cubic centimeter at room temperature.


A measure of an object's resistance to acceleration.
Objects with more mass require more force to move.


The compactness of matter within an object.
The density of the liquid increased when it was compressed.


The quantitative measure of the amount of substance.
The mass of the water in the bottle is 500 grams.


A measure of how much mass is contained in a given volume.
Gold has a higher density than aluminum.


The amount of matter present in an object.
The mass of the apple is 150 grams.


A property indicating the spacing of particles in a substance.
Gases typically have lower density than solids.


The total number of atoms and molecules in an object.
The mass of the air in the room is a combined total of all its constituent particles.


The degree to which something is filled or occupied.
The density of people in the concert was very high.


Public celebration of the Eucharist in the Roman Catholic Church and some Protestant churches.


The quality or condition of being dense.


The sacrament of the Eucharist.


The quantity of something per unit measure, especially per unit length, area, or volume.


Why do some objects float while others sink?

Objects with a density less than the fluid's density float, while those with greater density sink.

What does mass represent in an object?

Mass represents the amount of matter contained within an object.

How is density related to volume?

Density is calculated by dividing mass by volume.

What determines the density of a substance?

The density is determined by the mass of particles and their arrangement in space.

Does mass change in different gravitational fields?

No, mass remains consistent regardless of gravitational fields.

How is weight different from mass?

Weight is the force due to gravity on an object's mass and can vary with location.

Does changing the shape of an object affect its density?

No, changing shape doesn't affect density unless the internal arrangement of particles changes.

Can two objects have the same mass but different densities?

Yes, if they have different volumes, two objects can have the same mass but different densities.

Is mass conserved in chemical reactions?

Yes, mass is conserved in closed systems during chemical reactions.

Is mass scalar or vector?

Mass is a scalar quantity.

Why is the density of ice less than water?

Ice has a crystalline structure that occupies more space, resulting in a lower density than liquid water.

What is the center of mass?

The center of mass is the point where an object's mass is concentrated or balanced.

Why is understanding mass and density important?

Understanding mass and density helps in various applications, from engineering to understanding natural phenomena.

Does the density of a gas increase with pressure?

Yes, increasing pressure usually increases the density of gases.

Are mass and weight the same?

No, mass is the amount of matter, while weight is the force of gravity on that mass.

How is density important in buoyancy?

Buoyant force depends on the density difference between an object and the fluid it's in.

How is density affected in extraterrestrial environments?

Density might vary with different conditions, but it's mainly the mass-to-volume ratio that defines it.

What units are commonly used for density?

Common units for density include kg/m^3 and g/cm^3.

Does temperature affect the density of liquids?

Yes, temperature can affect the density of liquids, often causing them to expand or contract.

Is it possible for two substances to have the same density?

Yes, different substances can share the same density value.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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