# Definition:Mass Density

*This page is about Mass Density. For other uses, see Density.*

## Definition

**Mass density** is a physical quantity.

The **mass density** of a body is its mass per unit volume.

For a homogeneous body it is found by finding its total mass and dividing it by its total volume:

- $\rho = \dfrac m V$

where:

However, if the substance of the body varies throughout, then its **mass density** may be a function of position within the body.

### Symbol

The usual symbol used to denote **(mass) density** of a body is $\rho$ (Greek letter **rho**).

Some sources use $d$, but that has so many other uses that it may become confused with other things.

### Dimension

The dimension of **(mass) density** is $\mathsf {M L}^{-3}$: mass per unit volume.

### Units

- The SI units of
**mass density**are $\mathrm {kg} \, \mathrm m^{-3}$ (kilograms per cubic metre).

- The CGS units of
**mass density**are $\mathrm g \, \mathrm{cm}^{-3}$ or, less formally: $\mathrm g / \mathrm {cc}$ (grams per cubic centimetre).

- The FPS units of
**mass density**are $\mathrm {lb} \, \mathrm {ft}^{-3}$ (pounds per cubic foot).

## Area Mass Density

The **area mass density** of a two-dimensional body is its mass per unit area.

## Linear Mass Density

The **linear mass density** of a one-dimensional body is its mass per unit length.

## Also known as

**Mass density** is usually known just as **density**, but there are multiple usages for that term.

If it is necessary to distinguish between **mass density**, **area mass density** and **linear mass density**, the term **volumetric mass density** can be used.

$\mathsf{Pr} \infty \mathsf{fWiki}$ will generally use the unadorned term **density** in its exposition unless there is cause for confusion.

## Also see

- Results about
**mass density**can be found**here**.

## Sources

- 1921: C.E. Weatherburn:
*Elementary Vector Analysis*... (previous) ... (next): Chapter $\text I$. Addition and Subtraction of Vectors. Centroids: Definitions: $1$. Scalar and vector quantities - 1951: B. Hague:
*An Introduction to Vector Analysis*(5th ed.) ... (previous) ... (next): Chapter $\text I$: Definitions. Elements of Vector Algebra: $1$. Scalar and Vector Quantities - 1998: David Nelson:
*The Penguin Dictionary of Mathematics*(2nd ed.) ... (previous) ... (next):**density**:**1.** - 2008: David Nelson:
*The Penguin Dictionary of Mathematics*(4th ed.) ... (previous) ... (next):**density**:**1.**

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- 2014: Christopher Clapham and James Nicholson:
*The Concise Oxford Dictionary of Mathematics*(5th ed.) ... (previous) ... (next):**density**