One litre of water weighs one kilogramme. Generally, the volume of liquids is measured in litres, while the mass of solids is recorded in kilogrammes. Containers are frequently used to store water, and the volume of a container is always expressed in litres.
One litre is equivalent to one thousand millilitres. One millilitre is equivalent to one thousand cubic centimetres. Therefore, 1 millilitre is equal to 1 centimetre cubed. One cubic centimetre is equivalent to one gramme. Therefore, each millilitre and cubic centimetre of water weighs one gramme. This equates to 1,000 grammes of water per 1,000 millilitres. Therefore, one litre of water weighs precisely one kilogramme.