How to calculate density
Density tells you how much mass is packed into a given volume. It is why a small lump of lead is heavy while a big piece of foam is light. To find it, divide the mass of an object by the volume it takes up.
The density formula
Density = mass / volume. In SI units that is kilograms per cubic metre (kg/m3), though g/cm3 is also common in chemistry.
Worked example
An object with a mass of 10 kg that takes up 2 cubic metres has a density of 10 / 2 = 5 kg/m3.
Frequently asked questions
What is the density formula?
Density equals mass divided by volume. Rearranged, mass = density x volume, and volume = mass / density.
What is the density of water?
About 1,000 kg/m3, or 1 g/cm3. Objects denser than water sink; less dense ones float.
What units should I use?
Keep mass and volume in matching units. Kilograms and cubic metres give kg/m3; grams and cubic centimetres give g/cm3.