A cylinder can be considered as lots of circular discs stacked one above the other.

If the area of each circular disc is A and the height of the stack is h, then the volume = Ah.

Remember that the area of a circle with radius r = πr²

We can write this instead of A, so the volume of a cylinder with radius r and height h = πr²h

Example

Find the volume of this cylinder in cm³ to 3 significant figures.

Answer

Diameter = 6 cm

Radius = 6 ÷ 2 = 3 cm

Height = 12 cm

Volume = πr²h = π × 3² × 12 = 339.29 ≈ 339 cm³ (3 s.f.)