Density units explained: g/cm3, kg/m3 and lb/ft3
How the common density units relate, when to use each one, and how to convert between grams per cubic centimetre and kilograms per cubic metre.
Why density has so many unit pairs
Density is always a mass divided by a volume, but both halves can be measured in several ways, which is why you meet g/cm3, kg/m3, kg/L and pounds per cubic foot. Chemists tend to favour grams per cubic centimetre because a sugar cube sized sample is easy to weigh and measure. Engineers lean on kilograms per cubic metre because it is the SI base unit and slots straight into other physics equations. The value describes the same physical property in every case, only the scale changes.
Converting between g/cm3 and kg/m3
The most common conversion is between grams per cubic centimetre and kilograms per cubic metre, and the factor is exactly 1000. To go from g/cm3 to kg/m3 you multiply by 1000, and to go the other way you divide by 1000. That is why water reads as roughly 1 g/cm3 and 1000 kg/m3 at the same time. This calculator prints both numbers together so you never have to remember which direction to shift the decimal point.
Reading a density value in practice
A density figure tells you how tightly packed the matter is, so a larger number means more mass squeezed into the same space. Cork sits near 240 kg/m3 and floats, aluminium is around 2700 kg/m3, and lead is above 11000 kg/m3. Comparing a measured density against a known reference is a quick way to identify a material or spot an impurity. Because the tool converts every answer to kg/m3, you can line your result up against published tables without extra arithmetic.
Common mistakes with volume units
The biggest source of error is mixing up cubic centimetres and millilitres with litres, since 1 litre is 1000 cubic centimetres. Entering a volume in millilitres while the dropdown is set to litres will make your density look a thousand times too small. Always confirm the volume dropdown matches the number you typed, and remember that 1 mL equals 1 cm3 exactly, which is why both appear in the menu. Getting the volume unit right matters more than the mass unit because volume spans the widest range of everyday scales.