# Definition:Mass Density/Area

< Definition:Mass Density(Redirected from Definition:Area Mass Density)

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## Definition

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

### Symbol

The usual symbol used to denote **area mass density** is $\rho_A$ (Greek letter **rho**).

However, some sources simply use $\rho$ if the context makes it clear that it refers to **area mass density** rather than **volume mass density**.

Occasionally, $\sigma$ (Greek letter **sigma**) is also used, but this is more commonly used for surface charge density.

### Dimension

The dimension of **area mass density** is $\mathsf M \mathsf L^{-2}$: mass per unit area.

### Units

- The SI units of
**area mass density**are $\mathrm {kg} \ \mathrm m^{-2}$ (kilograms per square metre).

- The CGS units of
**area mass density**are $\mathrm g \ \mathrm{cm}^{-2}$ (grams per square centimetre).

Thus:

- $1 \ \mathrm g \ \mathrm{cm}^{-2} = 10 \ \mathrm{kg} \ \mathrm m^{-2}$

## Also known as

**Area mass density** is usually referred to just as **area density** when it is clear that **mass density** is the kind of **density** under discussion.

**Area (mass) density** is also known as **surface density**, **areal density** or **planar density**.

## Also see

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