Density is mass per unit volume: rho = m/V. The SI unit is kg/m^3. Common units include g/cm^3 and g/mL (which are equal: 1 g/cm^3 = 1 g/mL = 1000 kg/m^3).

What is the density of water?

Water has a density of approximately 1,000 kg/m^3 (1 g/cm^3 or 1 g/mL) at 4 degrees C. Density decreases slightly at higher temperatures. Ice is less dense (917 kg/m^3), which is why ice floats.

How do I know if an object will float?

An object floats if its density is less than the fluid it is placed in. For water (1,000 kg/m^3): wood (~600 kg/m^3) floats; iron (7,874 kg/m^3) sinks. The calculator shows a buoyancy indicator relative to water.

What is the densest natural element?

Osmium is the densest naturally occurring element at approximately 22,590 kg/m^3 (22.59 g/cm^3), slightly denser than iridium (22,560 kg/m^3). Gold (19,320 kg/m^3) and lead (11,340 kg/m^3) are also notably dense.

Density Calculator — Mass, Volume & Materials

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Density: the concept and its measurement

Density is an intensive property — it does not depend on the amount of material. A small piece of gold and a large piece of gold have the same density (19,320 kg/m^3). This makes density useful for material identification: if you measure the mass and volume of an unknown metal and find density close to 19,320 kg/m^3, it is likely gold.

Archimedes' principle states that a submerged object experiences a buoyant force equal to the weight of fluid it displaces. If the object is less dense than the fluid, the buoyant force exceeds gravity and the object floats. This is why massive ships float — the average density of the ship-plus-air system is less than water.

Common material densities

Air at sea level: 1.225 kg/m^3. Water: 1,000 kg/m^3. Wood (typical): 400-900 kg/m^3. Aluminum: 2,700 kg/m^3. Iron: 7,874 kg/m^3. Copper: 8,960 kg/m^3. Lead: 11,340 kg/m^3. Gold: 19,320 kg/m^3. Osmium: 22,590 kg/m^3.

Unit conversions: 1 g/cm^3 = 1,000 kg/m^3 = 1 g/mL. 1 lb/ft^3 = 16.018 kg/m^3. A density of 1 g/mL means 1 gram per milliliter, identical to 1 g/cm^3 since 1 mL = 1 cm^3 by definition.

Frequently asked questions

What is density?: Density is mass per unit volume: rho = m/V. The SI unit is kg/m^3. Common units include g/cm^3 and g/mL (which are equal: 1 g/cm^3 = 1 g/mL = 1000 kg/m^3).
What is the density of water?: Water has a density of approximately 1,000 kg/m^3 (1 g/cm^3 or 1 g/mL) at 4 degrees C. Density decreases slightly at higher temperatures. Ice is less dense (917 kg/m^3), which is why ice floats.
How do I know if an object will float?: An object floats if its density is less than the fluid it is placed in. For water (1,000 kg/m^3): wood (~600 kg/m^3) floats; iron (7,874 kg/m^3) sinks. The calculator shows a buoyancy indicator relative to water.
What is the densest natural element?: Osmium is the densest naturally occurring element at approximately 22,590 kg/m^3 (22.59 g/cm^3), slightly denser than iridium (22,560 kg/m^3). Gold (19,320 kg/m^3) and lead (11,340 kg/m^3) are also notably dense.