Density Converter
Convert density between kilograms per cubic metre, grams per cubic centimetre and imperial units.
Written by Rahman · Last reviewed
Quick answer
Density is mass per unit volume, in kilograms per cubic metre. One gram per cubic centimetre is 1,000 kg/m³ (which is the density of pure water) and one pound per cubic foot is 16.02 kg/m³. Because water sits at almost exactly 1 g/cm³, that value doubles as a quick test of whether something will float.
| Kilogram per cubic metre (kg/m³) | 1 |
| Gram per cubic centimetre (g/cm³) | 0.001 |
| Gram per cubic metre (g/m³) | 1000 |
| Kilogram per litre (kg/L) | 0.001 |
| Gram per litre (g/L) | 1 |
| Pound per cubic foot (lb/ft³) | 0.06242796058 |
| Pound per cubic inch (lb/in³) | 0.000036127292 |
| Pound per US gallon (lb/gal) | 0.008345404453 |
About the Density Converter
Density is the mass contained in a given volume of a substance. The SI unit is kilograms per cubic metre, while grams per cubic centimetre is common in chemistry and pounds per cubic foot in engineering.
This converter helps compare the density of materials and fluids quoted in different unit systems.
Specific gravity is a ratio, not a density
Specific gravity (also called relative density) expresses how dense a material is compared with a reference, normally water. Because it is a ratio of two densities it has no units at all, which is why it cannot be entered on this page directly.
The conversion is convenient in metric terms. Water is close to 1,000 kg/m³, or 1 g/cm³, so a specific gravity of 0.8 corresponds to 800 kg/m³. In customary units the same water is about 62.43 lb/ft³ or 8.345 lb per US gallon, which is why those two numbers appear so often in engineering tables.
- A specific gravity below 1 means the material floats in water; above 1 means it sinks.
- The reference temperature matters for precision, since water's density peaks near 4°C and falls either side.
- Gases are normally compared against air rather than water, so a gas specific gravity uses a different reference entirely.
API gravity runs backwards
The petroleum industry uses its own scale, and it is worth knowing about because it inverts the intuition. API gravity is derived from specific gravity but arranged so that higher numbers mean lighter, less dense oil, the opposite direction to every unit on this page.
Water sits at 10 degrees API by construction. Crude oils above that figure are lighter than water and float; those below are heavier. Light crudes command higher prices, so a rising API number and a falling density describe the same barrel.
- API gravity is dimensionless and cannot be converted here; convert its underlying specific gravity to density instead.
- Density varies with temperature for all fluids, so petroleum measurements are standardised to a reference temperature before comparison.
- Bulk density of a granular solid differs from the density of the material itself, because it includes the air between the particles.
Frequently Asked Questions
What is the density of water?
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Pure water has a density of about 1,000 kilograms per cubic metre, or 1 gram per cubic centimetre, at 4°C.
How do I convert g/cm³ to kg/m³?
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Multiply grams per cubic centimetre by 1,000 to get kilograms per cubic metre.
Why does density matter?
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Density determines whether an object floats or sinks and is used to identify materials and calculate weight from volume.