Density Converter
Convert density between metric and US/imperial units, including specific gravity with the water reference you choose. See how much a gallon or cubic foot weighs and which common materials have a similar density.
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How to use the Density Converter
- Enter the density, for example 7,850 for steel in kg/m³.
- Choose From and To units; all other units appear in the results.
- Pick a water reference if you work with specific gravity.
- Read the weights of a gallon, cubic foot and liter, plus the closest materials.
- Copy the results or download the material table.
Density conversion factors
Density is mass per unit volume (ρ = m ÷ V). Every conversion here goes through kilograms per cubic meter, the SI unit, using exact definitions: 1 lb = 0.45359237 kg, 1 ft = 0.3048 m, 1 in = 0.0254 m and 1 US gallon = 3.785411784 L.
| 1 unit | kg/m³ | g/cm³ | lb/ft³ |
|---|---|---|---|
| 1 kg/m³ (= 1 g/L) | 1 | 0.001 | 0.062428 |
| 1 g/cm³ (= g/mL = kg/L) | 1,000 | 1 | 62.428 |
| 1 lb/ft³ | 16.0185 | 0.0160185 | 1 |
| 1 lb/in³ | 27,679.9 | 27.6799 | 1,728 |
| 1 lb/gal (US) | 119.826 | 0.119826 | 7.48052 |
| 1 lb/gal (UK) | 99.7764 | 0.0997764 | 6.22884 |
| 1 oz/in³ | 1,729.99 | 1.72999 | 108 |
Specific gravity and the water reference
Specific gravity is the ratio of a density to that of water. Because water's density changes slightly with temperature, standards name a reference:
- 1,000 kg/m³: the everyday rounded value, fine for most practical work.
- 4 °C (999.972 kg/m³): water at its maximum density, common in science.
- 60 °F (999.016 kg/m³): used for petroleum products and API gravity.
- 20 °C (998.207 kg/m³): typical lab and room temperature.
The difference between references is under 0.2%, so it only matters for precise measurement.
Tips for using density
- Mass = density × volume. Steel at 7,850 kg/m³ weighs 7.85 kg per liter, or about 0.284 lb per cubic inch.
- Values for wood, concrete, fuels and stone vary with species, mix and grade; the material table gives typical figures, not exact ones.
- An object floats if its average density is lower than the liquid's; that is why steel ships float while solid steel sinks.
Frequently asked questions
How do I convert g/cm³ to kg/m³?
Multiply by 1,000. One cubic meter holds 1,000,000 cm³ and a kilogram is 1,000 g, so 1 g/cm³ = 1,000 kg/m³. Water at 4 °C is about 1 g/cm³ = 1,000 kg/m³.
How do I convert kg/m³ to lb/ft³?
Divide by 16.0185 (or multiply by 0.062428). Water at 1,000 kg/m³ is 62.43 lb/ft³, and steel at 7,850 kg/m³ is about 490 lb/ft³.
Are g/cm³, g/mL and kg/L the same?
Yes. A milliliter equals a cubic centimeter and a liter is 1,000 mL, so 1 g/cm³ = 1 g/mL = 1 kg/L = 1,000 kg/m³ = 1,000 g/L.
What is specific gravity?
Specific gravity (relative density) is a material's density divided by the density of water, so it has no units. A value above 1 sinks in water, below 1 floats. SG × 1,000 gives the approximate density in kg/m³; for precise work choose the water temperature your standard uses.
How much does a gallon of water weigh?
About 8.34 lb (3.785 kg) for a US gallon and about 10.02 lb (4.546 kg) for an imperial gallon, near room temperature. Enter 1 g/cm³ to see the exact figures.
What is API gravity?
API gravity is the petroleum industry's density scale: API = 141.5 ÷ SG − 131.5, with SG measured at 60 °F. Water is 10° API; lighter oils have higher API values. The converter shows it for densities typical of liquids.
Does density change with temperature?
Yes. Most materials expand when heated, so their density falls. Water is densest at about 4 °C (999.97 kg/m³) and is 998.2 kg/m³ at 20 °C. Gases change much more with temperature and pressure.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.