The density relationship
Density is how much mass is packed into a given volume: density = mass ÷ volume. Rearranging the same equation lets you find any one of the three when you know the other two — mass = density × volume, and volume = mass ÷ density. This tool solves whichever you choose, so it works for physics homework, material estimates and lab work alike.
Keep your units consistent
Density is always expressed as a mass unit over a volume unit — grams per cubic centimetre, kilograms per cubic metre, and so on. As long as the mass and volume you enter use units that match the density you want, the result is correct. Mixing units (grams with litres, say) will give a number in an unusual unit, so decide your system first.
Everyday reference points
Water is about 1 g/cm³ (1000 kg/m³), which is why things less dense than water float and denser ones sink. Aluminium is around 2.7 g/cm³ and steel about 7.85 g/cm³. Comparing your result against known materials is a quick sanity check.
Frequently asked questions
What units should I use?
Any consistent set. Common choices are g/cm³ or kg/m³. Just make sure the mass and volume match the density unit you have in mind.
Does temperature affect density?
Yes, slightly for most materials and more for gases, since volume changes with temperature. For everyday solids and liquids the effect is usually small.