The volume of a cylinder is given by:

Volume = Area of base x Height
V= r ^{2}H
where r is the radius of the circle and H is the height of the cylinder. 
Like prisms, cylinders have a volume equal to the area of the base times the height. In a cylinder, the base is a circle so the formula for the volume of a cylinder becomes
r
^{2}H, where r is the radius of the circle and H is the height of the cylinder.