Density relates an object's mass to its volume, and different industries default to different units — metric g/cm³ in a chemistry lab, SI kg/m³ in an engineering spec, or US customary lb/ft³ and lb/gal on a construction or fuel datasheet. This calculator converts between all five instantly, using kg/m³ as the common reference point.

How the conversion works

Every density unit expresses the same physical quantity — mass divided by volume — just scaled to different base units of mass and length. This calculator converts everything through kilograms per cubic meter (kg/m³), the SI base unit for density. To convert from unit A to unit B, the value in A is first multiplied by A's exact conversion factor into kg/m³, then divided by B's factor into kg/m³.

The conversion factors used are exact SI derivations: 1 g/cm³ = 1,000 kg/m³ (because 1 cm³ = 1×10⁻⁶ m³ and 1 g = 1×10⁻³ kg), 1 g/mL = 1,000 kg/m³ (a milliliter and a cubic centimeter are the same volume, so g/mL and g/cm³ are always numerically identical), 1 lb/ft³ = 16.018463373960138 kg/m³ (derived from the international pound of 0.45359237 kg and the international foot of 0.3048 m), and 1 lb/gal (US) = 119.82642731689663 kg/m³ (derived from the same pound and the US liquid gallon of 3.785411784 L).

Reading the result

The headline result shows your converted value along with a real-world comparison — for example, a value close to 1,000 kg/m³ is flagged as roughly water's density, while a value near 19,300 kg/m³ is flagged as close to gold. Use the Reference tab to see the same input expressed in all five units simultaneously, and the Common Materials tab to compare a range of everyday substances (air, wood, water, concrete, steel, gold) side by side without re-typing values.

Limits and edge cases

The material density figures shown in the Common Materials and Real-World Reference sections are typical reference values, not measured constants — actual density varies with temperature, pressure, moisture content, alloy composition, and manufacturing process. Concrete, for example, can range from about 2,200 to 2,500 kg/m³ depending on the mix. For engineering, regulatory, or safety-critical work, verify against a material-specific data sheet or lab measurement rather than relying on these reference values alone.