Density Calculator

First figure out the volume — measure the dimensions of a solid object, or use a graduated container for a liquid. Then put the object or material on a scale to find its mass. Finally, divide the mass by the volume: ρ = m / V. For example, a 500 cm³ object with a mass of 1000 g has a density of 1000 ÷ 500 = 2 g/cm³.

Density is calculated by dividing an object's mass by its volume: ρ = m / V. For example, if an object has a mass of 1000 grams and a volume of 500 cubic centimeters, its density is 1000 ÷ 500 = 2 grams per cubic centimeter (g/cm³), which is equivalent to 2000 kilograms per cubic meter (kg/m³). The result tells you how much matter is packed into a given amount of space — the higher the density, the more tightly packed the material is.

The core relationship is ρ = m / V, where ρ (rho) is density, m is mass, and V is volume. This formula can be rearranged to solve for either of the other variables: mass equals density times volume (m = ρ × V), and volume equals mass divided by density (V = m / ρ). Knowing any two of the three values lets you solve for the third, which is exactly how this calculator's Density, Mass, and Volume modes work.

The most common units for density are grams per cubic centimeter (g/cm³) for solids and liquids, and kilograms per cubic meter (kg/m³) in the SI system — 1 g/cm³ equals exactly 1000 kg/m³. Other units you'll encounter include kilograms per liter (kg/L, numerically equal to g/cm³), and pounds per cubic foot (lb/ft³) in the US customary system. Scientists typically default to kg/m³ or g/cm³ because they scale cleanly with the metric mass and volume units used in most lab work.

Because every pure substance has a consistent density under given conditions, measuring an object's mass and volume and computing ρ = m / V lets you compare the result against known reference values — for example, pure gold is 19.32 g/cm³, aluminum is 2.70 g/cm³, and water is 1.00 g/cm³. If a sample's calculated density is far from the expected value for a claimed material, it signals impurities, hollow spaces, or a completely different substance. This principle also explains why objects less dense than water float and objects denser than water sink.

Density changes with temperature because most materials expand (increase in volume) as they heat up and contract as they cool down, while mass stays constant — since density is mass divided by volume, a larger volume at the same mass means a lower density. Water is a notable exception near its freezing point: it is actually less dense as a solid (ice) than as a liquid, which is why ice floats. This is why precise density measurements, especially for liquids and gases, are usually reported alongside the temperature at which they were measured.

Rearrange the density formula to solve for volume: V = m / ρ. For instance, if a metal block has a mass of 540 grams and a known density of 2.70 g/cm³ (aluminum), the volume is 540 ÷ 2.70 = 200 cm³. This approach is useful whenever you know a material's identity (and therefore its standard density) and its mass, but can't directly measure its volume — such as with irregularly shaped objects.