Volume Calculator
Find the volume and surface area of common 3D shapes, with litres and gallons.
About this tool
Choose a shape, enter its measurements in one unit and get the volume, the surface area and the capacity in litres and US and UK gallons. Uses the standard formulas for each solid; everything is worked out in your browser.
Volume is how much space a 3D object takes up, or how much it can hold: the water in a fish tank, the soil for a planter, the concrete for a slab or the air in a room. Pick a shape, enter its measurements and the calculator gives the volume in cubic units, its capacity in litres and gallons, and the surface area, which is useful when you need to paint or wrap it.
How to use the Volume Calculator
- Choose the shape: box, cube, cylinder, sphere, cone or square pyramid.
- Pick the unit your measurements are in.
- Enter the measurements shown; the labels change with the shape.
- Read the volume, the litres and gallons, and the surface area.
A 40 × 30 × 25 cm fish tank
A box-shaped tank 40 cm long, 30 cm wide and 25 cm high holds 40 × 30 × 25 = 30 000 cm³. Because 1 litre is 1 000 cm³, that is 30 litres, or about 7.9 US gallons. Fill it to 2 cm below the top and the water volume is 40 × 30 × 23 = 27 600 cm³, or 27.6 litres.
Volume formulas and units
A box is length × width × height, and a cube is side³. A cylinder is π × radius² × height: the area of the circular base times the height. A cone or pyramid holds exactly one third of the cylinder or box with the same base and height. A sphere is 4⁄3 × π × radius³. Volumes are in cubic units, so the conversion factor is cubed: 1 m is 100 cm, but 1 m³ is 1 000 000 cm³, which is 1 000 litres. If you measure a diameter, halve it to get the radius. For irregular shapes, split them into simpler solids and add the volumes together.
Frequently asked questions
How many litres are in a cubic metre?
One cubic metre is 1 000 litres, and one litre is 1 000 cubic centimetres.
How do I work out the volume of a round pool?
Use the cylinder: π × radius² × average depth. A pool 4 m across (radius 2 m) and 1.2 m deep holds about 15.1 m³, or 15 100 litres.
How much concrete do I need for a slab?
Multiply length × width × thickness in metres to get cubic metres, then add about 5 to 10% for waste.
What is the difference between volume and surface area?
Volume is the space inside, in cubic units. Surface area is the total area of the outside faces, in square units.