Density Conversion Calculator
Enter a density value, choose the unit you are converting from, and pick the unit you want. The result updates instantly, along with the conversion factor and a worked example showing the arithmetic. Switch between metric units like kg/m³ and g/cm³ or imperial units like lb/ft³ and lb/in³. A reference table of common material densities is included below.
Formula
Worked example
To convert 1 g/cm³ to kg/m³: 1 g/cm³ × 1000 (g/cm³ to kg/m³ factor) = 1000 kg/m³. To then convert to lb/ft³: 1000 kg/m³ ÷ 16.018 = 62.43 lb/ft³. Water has a density of exactly 1 g/cm³, so 1 g/cm³ = 1000 kg/m³ = 62.43 lb/ft³.
What is density and why does it matter?
Density is the mass of a substance divided by the volume it occupies (d = m / V). It is the property that determines whether a solid sinks or floats in a liquid, how much a fixed volume of material weighs, and how concentrated a solution is. Engineers use density to estimate the weight of structures and components; chemists use it to identify unknown liquids; geologists use it to study rock and mineral composition. In the SI system, the standard unit is kilogram per cubic metre (kg/m³), but in practice many fields prefer the more human-scale gram per cubic centimetre (g/cm³) or, in the United States, pounds per cubic foot (lb/ft³).
How the conversion works
Every density unit can be expressed as a fixed multiple of kg/m³. To convert between any two units, the calculator first multiplies the input by the factor that converts the source unit to kg/m³, then divides by the factor for the target unit. For example, 1 g/cm³ = 1000 kg/m³, and 1 lb/ft³ = 16.018 kg/m³, so 1 g/cm³ to lb/ft³ is 1000 / 16.018 = 62.43 lb/ft³. The same pivot approach covers all 20 unit pairs without a separate lookup table for every combination.
Metric units: understanding the relationships
Within the metric system, several density units are numerically equal. Grams per millilitre (g/mL), grams per cubic centimetre (g/cm³), kilograms per litre (kg/L), and kilograms per cubic decimetre (kg/dm³) are all exactly 1000 kg/m³ per unit. This is because 1 litre = 1 dm³ = 1000 cm³ = 1000 mL. The milligram per litre (mg/L) unit is commonly used in water quality reporting and equals 0.001 kg/m³, so 1 mg/L is numerically identical to 1 part per million (ppm) by mass in dilute aqueous solutions. Grams per cubic metre (g/m³) is used for very low-density gases and aerosols.
Imperial and US customary density units
The most common imperial density unit in construction and engineering is the pound per cubic foot (lb/ft³). Fluid density is often quoted in pounds per US gallon (lb/gal) in the petroleum and chemical industries. Pounds per cubic inch (lb/in³) appears in materials engineering when dealing with dense metals, because it keeps the numbers compact: steel is about 0.284 lb/in³ compared with 490 lb/ft³. The slug per cubic foot (slug/ft³) belongs to the foot-pound-second system of mechanics; 1 slug/ft³ = 515.38 kg/m³. Long and short ton per cubic yard appear in bulk-material shipping. When converting between US and UK gallons, note that the imperial gallon (4.546 L) is larger than the US gallon (3.785 L), so lb/gal values differ between the two systems.
Common material densities
| Material | g/cm³ | kg/m³ | lb/ft³ |
|---|---|---|---|
| Air (sea level) | 0.0012 | 1.2 | 0.075 |
| Cork | 0.12 | 120 | 7.5 |
| Oak wood | 0.77 | 770 | 48.1 |
| Ice | 0.917 | 917 | 57.2 |
| Water (4 °C) | 1.000 | 1000 | 62.4 |
| Sea water | 1.025 | 1025 | 64.0 |
| Concrete | 2.30 | 2300 | 143.6 |
| Aluminium | 2.70 | 2700 | 168.5 |
| Glass | 2.50 | 2500 | 156.1 |
| Titanium | 4.51 | 4510 | 281.6 |
| Iron (pure) | 7.87 | 7870 | 491.3 |
| Steel (mild) | 7.85 | 7850 | 490.1 |
| Copper | 8.94 | 8940 | 558.1 |
| Lead | 11.34 | 11340 | 708.0 |
| Mercury | 13.55 | 13550 | 846.0 |
| Gold | 19.30 | 19300 | 1205 |
Approximate densities at 20 °C and standard atmospheric pressure. Values may vary with grade, temperature, and purity.
Frequently asked questions
How do I convert g/cm³ to kg/m³?
Multiply by 1000. One gram per cubic centimetre equals 1000 kilograms per cubic metre, because 1 cm³ = 0.000001 m³ and 1 g = 0.001 kg, so the ratio is 0.001 / 0.000001 = 1000. For example, 2.7 g/cm³ (aluminium) = 2700 kg/m³.
How do I convert kg/m³ to lb/ft³?
Divide by 16.0185 (or multiply by 0.06243). For a quick mental check: water at 4 °C is 1000 kg/m³ = 62.43 lb/ft³, so dividing by 16 gives a rough answer within 0.1 %.
What is the density of water in different units?
Pure water at 4 °C (its maximum-density point) is exactly 1.000 g/cm³ = 1000 kg/m³ = 1.000 kg/L = 62.43 lb/ft³ = 8.345 lb/US gal = 0.03613 lb/in³. At room temperature (20 °C) water is very slightly less dense at 0.9982 g/cm³.
Why are g/mL, g/cm³, and kg/L all the same number?
Because one litre equals one cubic decimetre, which equals 1000 cubic centimetres, and one millilitre equals one cubic centimetre. So 1 g/mL = 1 g/cm³ = 1 kg/dm³ = 1 kg/L. This means the density of water can be written as any of those without changing the number.
What is a slug per cubic foot used for?
The slug is the unit of mass in the foot-pound-second engineering system. One slug equals 14.594 kg. Slug per cubic foot is used in aerospace and fluid mechanics calculations that use imperial units: for example, the density of air at sea level is about 0.00237 slug/ft³ (1.225 kg/m³). Most modern engineering has moved to SI, but slug/ft³ still appears in older American aerospace references.
Does density change with temperature?
Yes. Most materials expand when heated, increasing volume while mass stays constant, which lowers density. The effect is small for solids and liquids but significant for gases: air density drops roughly 0.35 % per degree Celsius rise at constant pressure. Reference tables normally state the temperature at which a value applies, usually 20 °C (68 °F) for common engineering materials.