A unit of density expressing mass in grams per volume in cubic centimeters.Grams per cubic centimeter (g/cm³) is a unit of density, which measures how much mass is packed into a given volume. It is the standard unit for density in the centimeter-gram-second (CGS) system, and it is widely used in everyday contexts because it gives convenient numbers for common materials. For example, water has a density of about 1 g/cm³, which makes it a natural reference point: materials with a density greater than 1 g/cm³ sink in water, while those with a lower density float.
The unit follows from the metric system's definitions, where the gram was originally defined as the mass of one cubic centimeter of water at its maximum density (around 4°C). This historical link makes the unit particularly natural for scientific work.
Density is calculated by dividing an object's mass by its volume. In this unit, mass is measured in grams and volume in cubic centimeters. A cubic centimeter is exactly one milliliter, so the unit is equivalent to grams per milliliter (g/mL). This equivalence makes it easy to measure the density of liquids with a graduated cylinder and a scale.
It is used in materials science to identify substances, in geology to classify rocks and minerals, and in engineering to calculate buoyancy and structural loads.
The density of the Earth's core is about 13 g/cm³, similar to lead, yet the average density of the entire planet is only about 5.5 g/cm³.
