Volume unit converter

The calculator converts volume between mm³, cm³, millilitres, dm³, litres, hectolitres, m³ and km³. Choose the unit of the volume you enter and the unit of the result next to the boxes. Water bills are usually based on cubic metres, m³: one cubic metre is 1,000 litres, roughly seven full baths.

How it works

A cubic metre is the volume of a cube with sides of 1 metre. Measured in decimetres, the side is 10 dm, and the volume of a cube is 10 · 10 · 10 = 1,000 dm³. So volumes are converted in thousands. And since 1 dm³ is exactly 1 litre, a cubic metre holds 1,000 litres.

A few typical conversions:

• 1 m³ = 1,000 l,
• 0.5 l = 500 ml (a standard bottle),
• 250 cm³ = 250 ml = 0.25 l (a mug),
• 3 hl = 300 l (a rainwater butt).

Things to watch out for

Volume cannot be converted like length or area: 1 m³ = 1,000 dm³ = 1,000 l, not 10 or 100. All three dimensions are converted at once, so you multiply by ten three times.

The second trap is that litres and millilitres are not cubic units, but they match them exactly: 1 l = 1 dm³ and 1 ml = 1 cm³. So when you work out the volume of a cuboid or volume of a cylinder in decimetres, you have litres straight away. For tanks, there is a ready-made cylindrical tank volume calculator.

The calculator does not offer decilitres (dl), but they are easy: 1 dl = 100 ml = 0.1 l.