Density Converter
Convert between kg/m³, g/cm³, g/mL, lb/ft³, and lb/gallon.
How density conversion works
Density is mass per unit of volume, so every unit here combines a mass unit (kilograms, grams, pounds) with a volume unit (cubic meters, cubic centimeters, cubic feet, gallons). Everything converts through kilograms per cubic meter, the SI unit.
Multiply your value by the number of kg/m³ in its unit, then divide by the number of kg/m³ in the target unit. The metric units differ by simple powers of ten: 1 g/cm³ and 1 g/mL are both 1,000 kg/m³.
Worked example
Aluminium has a density of about 2,700 kg/m³. In g/cm³ that is 2,700 ÷ 1,000 = 2.7. In pounds per cubic foot, divide by about 16.018 kg/m³ per lb/ft³: the result is about 168.56 lb/ft³.
Common conversions
| Conversion | Result |
|---|---|
| Water, 1,000 kg/m³ in lb/ft³ | 62.427961 lb/ft³ |
| Water, 1 g/mL in lb/gal | 8.345404 lb/gal |
| Seawater, 1.025 g/mL in lb/gal | 8.55404 lb/gal |
| Aluminium, 2.7 g/cm³ in kg/m³ | 2,700 kg/m³ |
| Steel, 7,850 kg/m³ in g/cm³ | 7.85 g/cm³ |
| Ice, 917 kg/m³ in g/cm³ | 0.917 g/cm³ |
| Air, 1.225 kg/m³ in g/cm³ | 0.001225 g/cm³ |
Which unit to expect
Kilograms per cubic meter is the engineering and SI standard, grams per cubic centimeter is common in labs and materials tables, pounds per cubic foot is used in US construction and engineering, and pounds per gallon appears for US liquids such as fuels and coatings. The material values above are typical figures near room temperature; real densities shift with temperature, composition and alloy. Pounds per gallon here means the US gallon, which is smaller than the UK gallon.
Frequently asked questions
Why are g/cm³ and g/mL the same number?
Because a cubic centimeter and a milliliter are exactly the same volume by definition (1 cm³ = 1 mL) — so any density expressed in grams per cubic centimeter is numerically identical to grams per milliliter.
Why does water's density matter as a reference point?
Water's density (about 1,000 kg/m³) is used as the baseline for specific gravity, a common way materials are compared — a material with a specific gravity above 1 sinks in water, and below 1 it floats.