# Volume

In this section of Revision Maths you will learn how to calculate the volume of prisms, pyramids and frustums.

Volume is a 3D Measurement so we need to always write answers as cubed numbers, for example CM^{3} or M^{3}.

**Volume of a Prism**

To calculate the volume of a prism you need to use this formula: Area of a cross-section x height or length.

In the example above the volume = 4 x 5 x8 = 160cm^{3}

To find out how to work out the area of a 2D shape **click here**.

**Volume of a Pyramid**

To calculate the volume of a pyramid you use this formula: 1/3 area of a cross section x height.

In the example above the volume = 1/3 x 4 x 5 x 8 = 53.33cm^{3 }(to 4.s.f).

**Volume of a Frustum**

A frustum is made by cutting the top end of a cone to calculate the volume of a frustum use the formula below:

1/3 π R^{2 }H – 1/3 πr^{2}h

The second half of the formula is how to work out the volume of the entire cone.

In the example above 1/3π [(8^{2} x 11) – (4^{2} x 5)

So the volume of this frustum = 208 πcm^{3} or 653cm^{3} (to 3 s.f)