How to use the density converter
- Type a density in the From box. Decimals (7.85) and thousands separators (7,850) both work, but negative values are rejected.
- Pick the unit you have in the first menu and the unit you want in the second. The To box and the result line update as you type.
- To work backwards, type in the To box and the From box follows.
- Press Swap units to flip the direction, or read Same density in every unit to see your number in all twelve other units at once.
How the conversion works
Every unit is stored as a size in kilograms per cubic meter. The tool multiplies your number by the size of the From unit, then divides by the size of the To unit: result = value × From size ÷ To size. The pound is exactly 0.45359237 kg, the foot exactly 0.3048 m and the US gallon exactly 3.785411784 L, so 1 lb/ft³ = 16.018463 kg/m³, 1 lb/in³ = 27,679.905 kg/m³ and 1 lb/US gal = 119.82643 kg/m³. These match NIST Guide to the SI, Appendix B.8. Ounces are weight ounces, not fluid ounces.
Specific gravity is density divided by that of water, which peaks at about 999.972 kg/m³ near 4 °C, so 1,000 kg/m³ reads 1.000028. In everyday work g/cm³ and specific gravity are effectively the same number.
Worked example with the default values
With 1000 in the From box, kg/m³ as the From unit and lb/ft³ as the To unit, the result line reads 1,000 kg/m³ = 62.427961 lb/ft³, because 1,000 ÷ 16.018463 = 62.427961. The reverse line reads 1 lb/ft³ = 16.018463 kg/m³, and the grid shows the same density as 8.3454045 lb/US gal and a specific gravity of 1.000028.
Typical densities
| Material | kg/m³ | g/cm³ | lb/ft³ |
|---|---|---|---|
| Air at sea level, 15 °C | 1.225 | 0.001225 | 0.076474252 |
| Ice at 0 °C | 917 | 0.917 | 57.24644 |
| Fresh water | 1,000 | 1 | 62.427961 |
| Seawater | 1,025 | 1.025 | 63.98866 |
| Aluminum | 2,700 | 2.7 | 168.55549 |
| Steel | 7,850 | 7.85 | 490.05949 |
| Lead | 11,340 | 11.34 | 707.93307 |
| Gold | 19,300 | 19.3 | 1,204.8596 |
Values are typical handbook figures at room temperature; real samples vary with alloy, purity and temperature. To find the weight of a given volume, get the volume from the volume converter or cylinder volume calculator, multiply by the density, and show the mass with the weight converter. Other units are in the unit converter.
Limits and edge cases
Density changes with temperature and pressure, and this page only changes units: it does not correct for them, so warm water, hot oil or compressed gas will differ from the table. Letters and slashes are blocked with a hint, and anything above 1e24 is refused. UK and US gallons differ by about 20 percent, so lb/UK gal and lb/US gal are separate units.
Sources: NIST Guide to the SI, Appendix B.8; USGS Water Science School, water density.
Density converter FAQ
How do I convert g/cm³ to kg/m³?
Multiply by 1,000. For example, 2.7 g/cm³ (aluminum) is 2,700 kg/m³. To go back, divide by 1,000. The same factor works for g/mL and kg/L.
What is the density of water in lb/ft³?
Water is about 1,000 kg/m³, which is 62.427961 lb/ft³. That is also 8.3454045 lb per US gallon.
How much does a gallon of water weigh?
About 8.345 pounds for a US gallon, using 1,000 kg/m³ for water. A UK gallon of water weighs about 10.022 pounds.
How do I get specific gravity from density?
Divide the density in kg/m³ by 999.972, the density of water at 4 °C. Steel at 7,850 kg/m³ has a specific gravity of 7.85. In g/cm³ the number is almost the same as the specific gravity.
Will a material float in water?
It floats if its density is below water, about 1,000 kg/m³ or 1 g/cm³ for fresh water. Ice at about 917 kg/m³ floats, while aluminum at 2,700 kg/m³ sinks. Seawater is denser at about 1,025 kg/m³.