🧊 Density

Density Converter

Convert mass per unit volume for fluids, metals, powders and gases. Enter a value, choose units and press Convert.

Written and reviewed by SM Arijul Islam · Last reviewed 28 October 2026 · Editorial standards · Report an error

About the density converter

Density is mass divided by volume. The SI unit is kilograms per cubic metre, but laboratory work often uses grams per cubic centimetre, and shipping uses pounds per cubic foot. Since 1 g/cm³ equals 1,000 kg/m³, moving between metric units is simply a matter of powers of ten.

Reference densities

Water at 4 °C: 1,000 kg/m³ = 1 g/cm³
Sea water: about 1,025 kg/m³
Air at sea level: about 1.225 kg/m³
Steel: about 7,850 kg/m³
Gold: 19,320 kg/m³

Density × volume = mass. Combine with the Volume Converter to work out the weight of a shipment.

How to convert density

Density is mass per unit volume. In SI it is kilograms per cubic metre (kg/m³); the CGS system uses grams per cubic centimetre (g/cm³), and 1 g/cm³ is exactly 1,000 kg/m³. Imperial units such as pounds per cubic foot and pounds per US gallon remain common in engineering, shipping and brewing. Water is the reference point at about 1,000 kg/m³ at 4 °C, which is why specific gravity is quoted relative to it.

Common density conversions

One gram per cubic centimeter expressed in other units of density
Unit	1 gram per cubic centimeter equals
Kilogram per cubic meter (kg/m³)	1,000
Gram per liter (g/L)	1,000
Pound per cubic foot (lb/ft³)	62.427961
Pound per US gallon (lb/gal)	8.3454045
Gram per milliliter (g/mL)	1
Kilogram per liter (kg/L)	1

Everyday uses

Choosing materials and estimating shipping weight
Buoyancy, flotation and ballast
Chemistry and laboratory work
Brewing, winemaking and baking
Comparing metals, plastics and composites

Frequently asked questions

What is the density of water?

About 1,000 kg/m³, 1 g/cm³ or 62.428 lb/ft³ at 4 °C, its point of maximum density.

Is a denser object always heavier?

No. Density is mass per volume, so a small dense object can easily weigh less than a large light one.

How do I convert kg/m³ to g/cm³?

Divide by 1,000. Going the other way, multiply by 1,000.

What is specific gravity?

A unitless ratio comparing a substance's density with that of water, so 1.0 means the same density as water.

More worked examples

Water reaches its maximum density at about 4 °C, where it is 1,000 kg/m³, or 1 g/cm³.
Mild steel is around 7,850 kg/m³, so a cubic metre of it weighs nearly eight tonnes.
Air at sea level and 15 °C is about 1.225 kg/m³.
One g/cm³ is exactly 1,000 kg/m³, because a cubic metre holds a million cubic centimetres.

Typical densities

Typical densities of common materials at room temperature
Material	Density
Air, sea level, 15 °C	about 1.225 kg/m³
Water at 4 °C	1,000 kg/m³
Sea water	about 1,025 kg/m³
Ice	917 kg/m³
Aluminium	2,700 kg/m³
Mild steel	about 7,850 kg/m³
Lead	11,340 kg/m³
Gold	19,320 kg/m³

Common mistakes to avoid

Using 1 g/cm³ for every liquid. Cooking oils are around 0.9 and mercury is about 13.6, so the assumption fails badly outside water.
Forgetting that density changes with temperature. Water is densest near 4 °C and expands both as it warms and as it freezes.
Confusing density with specific gravity. Specific gravity is a ratio to water, so it has no units at all.
Mixing lb/ft³ and kg/m³ without the factor. One pound per cubic foot is about 16.018 kg/m³.

Further questions

Is 1 g/cm³ the same as 1,000 kg/m³?

Yes, exactly. There are one million cubic centimetres in a cubic metre, and one million grams in a tonne.

Why does ice float on water?

Because ice is less dense, about 917 kg/m³ against 1,000 kg/m³ for liquid water. Water is unusual in expanding when it freezes.

Sources and standards

Density is mass per unit volume, so its factors combine the exact kilogram and cubic metre definitions. NIST SP 811 supplies the customary equivalents, including the pound per cubic foot, and the page labels any material figure that is a nominal handbook value rather than a definition.