Density Calculator – Find Mass, Volume or Density ρ=m/V

Density (ρ) is a measure of mass per unit volume. It tells you how much "stuff" is packed into a given space. The formula is ρ = m / V, where m is mass and V is volume. For example, if an object has a mass of 10 kg and occupies a volume of 2 m³, its density is 5 kg/m³. Density is an intensive property, meaning it doesn't depend on the amount of substance—a drop of water and a swimming pool of water have the same density (~1000 kg/m³).

The SI unit for density is kg/m³ (kilograms per cubic meter). Other common units include:

• g/cm³ or g/mL — commonly used for solids and liquids (1 g/cm³ = 1000 kg/m³)
• lb/ft³ — used in imperial/US systems (1 lb/ft³ ≈ 16.02 kg/m³)
• lb/in³ — used for high-density materials like metals (1 lb/in³ ≈ 27,680 kg/m³)

Use our calculator above to instantly convert between any of these units.

Rearrange the density formula to solve for mass: m = ρ × V. Simply multiply the density by the volume. For instance, if water has a density of 1000 kg/m³ and you have 3 m³ of water, the mass is 1000 × 3 = 3000 kg. Use our calculator's "Find Mass" mode to do this automatically with unit conversions.

Rearrange the formula to solve for volume: V = m / ρ. Divide the mass by the density. For example, if you have 500 kg of iron (density ~7874 kg/m³), the volume is 500 / 7874 ≈ 0.0635 m³ (or about 63.5 liters). Select "Find Volume" mode in the calculator to compute this with any unit combination.

Ice floats because its density (~917 kg/m³) is less than the density of liquid water (~1000 kg/m³). This is unusual—most substances are denser in their solid form. Water expands when it freezes due to its crystalline molecular structure, decreasing its density. Objects with density lower than the fluid they're in will float; objects with higher density will sink.

For most substances, density decreases as temperature increases because the material expands (volume increases) while mass remains constant. Water is a notable exception: its maximum density occurs at about 4°C (1000 kg/m³). Both heating above 4°C and cooling below 4°C (toward freezing) cause water to expand and become less dense. This property is crucial for aquatic life, as it prevents lakes from freezing solid from the bottom up.