MatterLab

Density Calculator

ρ = m / V, in kg/m³.

Mass (kg)

Volume (m³)

Density (kg/m³)

2,500

ρ = m / V

What you entered

Mass (kg): 5Volume (m³): 0.002

1
Density: ρ = m ÷ V
5 ÷ 0.002= 2500

Result

Density (kg/m³): 2,500

5kg packed into 0.002m³ gives a density of 2,500 kg/m³ — water is 1000 kg/m³ for comparison.

Density of common materials

Density is mass divided by volume, in kilograms per cubic metre. Water is 1000 by definition of the original metric system.

Mass (kg)	Volume (m3)	Density (kg/m3)	Material
500	2	250.00	Softwood, roughly
917	1	917.00	Ice
1000	1	1000.00	Fresh water
1	0.001	1000.00	1 kg in 1 litre - also water
7850	1	7850.00	Steel
19300	1	19300.00	Gold

Ice at 917 is less dense than water at 1000, which is why it floats and why water pipes burst when they freeze - water is one of very few substances that expands on solidifying. Rows three and four give identical densities from different scales, since density is intensive: it does not depend on how much you have. Divide by 1000 to get grams per cubic centimetre, the unit most tables use, so steel is 7.85 g/cm3. Anything below 1000 floats in water; gold at 19.3 times water's density does not.

Why some things float and others sink

An object floats in a fluid if its density is lower than the fluid's — a steel ship floats not because steel is light, but because its overall shape displaces enough water to make its effective density lower than water's.

A useful reference point

Water sits at almost exactly 1,000 kg/m³, which makes it a handy mental benchmark — most everyday liquids and many solids fall within an order of magnitude of that number.

Frequently asked questions

A gold bar measures 7 × 3.25 × 1.75 cm and weighs 1 kg. Is it real gold?

Volume = 39.8 cm³ = 0.0000398 m³. Density = 1/0.0000398 ≈ 25,126 kg/m³. Real gold is 19,320 kg/m³, so this bar is far too dense for its claimed size — either the dimensions or the mass are wrong.

Why does oil float on water?

Oil has a density of about 800-920 kg/m³, while water is ~1,000 kg/m³. Since oil is less dense, it floats. This is also why oil spills spread on the ocean surface rather than sinking. See the buoyancy calculator for the force analysis.

How is density related to buoyancy?

An object floats if its average density is less than the fluid's density. A steel ship (steel density ~7,800 kg/m³) floats because its hollow shape gives it an average density below water's 1,000 kg/m³. See the buoyancy calculator for Archimedes' principle.

Can I use this to identify an unknown material?

Yes — density is a characteristic property. Measure mass and volume, calculate ρ = m/V, then compare: aluminum is 2,700 kg/m³, iron 7,874, copper 8,960, lead 11,340, gold 19,320. A measured density near 8,960 strongly suggests copper.