The Surprising Truth Behind the Measurement of 1 P Litre We weren’t able to create a summary for you. Refresh your page to try again. The litre is often also used in some calculated measurements , such as density (kg/L), allowing an easy comparison with the density of water. One litre of water has a mass of almost exactly one kilogram when measured at its maximal density, which occurs at 3.984 °C. The litre is often also used in some calculated measurements , such as density (kg/L), allowing an easy comparison with the density of water. One litre of water has a mass of almost exactly one kilogram when measured at its maximal density, which occurs at 3.984 °C. Before diving into the liter itself, let's touch on what it measures : volume. Simply put, volume is the amount of three-dimensional space a substance (whether solid, liquid, or gas) occupies. When you measure a cup of flour or a gallon of gasoline, you are measuring volume. Before diving into the liter itself, let's touch on what it measures : volume. Simply put, volume is the amount of three-dimensional space a substance (whether solid, liquid, or gas) occupies. When you measure a cup of flour or a gallon of gasoline, you are measuring volume. The litre is often also used in some calculated measurements, such as density (kg/L), allowing an easy comparison with the density of water. One litre of water has a mass of almost exactly one kilogram when measured at its maximal density, which occurs at 3.984 °C. Before diving into the liter itself, let's touch on what it measures: volume.