Free online density converter. Convert grams per cubic centimeter, kilograms per cubic meter, pounds per cubic foot, and more — for chemistry, engineering, cooking, and material science. Accurate, instant, no sign-up.
g/cm³ • kg/m³ • lb/ft³ • lb/in³
Convert solution and reagent densities between g/mL and kg/m³. Specific gravity tells you if a substance floats or sinks in water.
Material densities in lb/ft³ (US) vs kg/m³ (SI) for structural load, buoyancy, and weight estimates.
Convert ingredient densities to translate between weight and volume measurements in recipes.
Density is mass per unit volume, and the reference substance is water: exactly 1 gram per cubic centimeter (g/cm³), which equals 1,000 kilograms per cubic meter (kg/m³) or 62.43 pounds per cubic foot (lb/ft³) at 4°C. The g/cm³ unit is most common in chemistry (and equals g/mL, since 1 cm³ = 1 mL), while kg/m³ is the SI standard used in physics and engineering. In the US construction and materials industries, lb/ft³ dominates, and precision machining uses lb/in³.
Specific gravity is density relative to water (dimensionless): a substance with specific gravity below 1 floats, above 1 sinks. Numerically, specific gravity equals the density in g/cm³. For example, gold has a density of 19.3 g/cm³ (specific gravity 19.3), aluminum is 2.7 g/cm³, and gasoline is about 0.74 g/cm³ (which is why it floats on water). Converting density correctly is essential for buoyancy calculations, material selection, shipping weight estimates, and verifying the purity of metals and liquids.
Water: 1.0 g/cm³. Gasoline: 0.74. Milk: 1.03. Honey: 1.42. Mercury: 13.6. Seawater: 1.025. Olive oil: 0.92 (floats on water).
Aluminum: 2.7 g/cm³. Iron: 7.87. Steel: 7.85. Copper: 8.96. Lead: 11.34. Gold: 19.3. Titanium: 4.51 (strong & light).
Concrete: 2,400 kg/m³ (150 lb/ft³). Wood (pine): 500 kg/m³. Brick: 1,920 kg/m³. Glass: 2,500 kg/m³.
Density relative to water. SG < 1 floats, SG > 1 sinks. Equals density in g/cm³. Used to test battery acid, fuel, and precious metals.
Density is mass per unit volume, and it is the bridge between the two whenever a material must be bought by weight and used by volume, or vice versa. The metric system was designed to make this easy: water at 4 °C has a density of almost exactly 1 g/cm³, which is 1,000 kg/m³ and 1 kg per litre, so for water the numbers coincide across units. Nothing else is so convenient. Specific gravity — density relative to water — is dimensionless and therefore identical in every unit system, which is why it is the preferred figure in trade specifications.
ρ = mass ÷ volumekg/m³ = value × factor_from1 g/cm³ = 1,000 kg/m³ · 1 lb/ft³ = 16.0185 kg/m³ · SG = ρ ÷ 1,000where:
Assumptions: Density varies with temperature and, for gases, strongly with pressure. Liquid figures normally assume 20 °C unless a temperature is stated.
A solvent density converted into the units a US specification would use.
Result0.79 g/cm³ = 790 kg/m³ = 49.32 lb/ft³ (SG 0.79)
Because ethanol is less dense than water it floats, and because the difference is 21% the weight saving on bulk shipping is substantial. Specific gravity below 1 always means the material floats on water; above 1 it sinks.
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