Density Converter
Convert density between kg/m³, g/cm³, g/mL, kg/L, lb/ft³, and lb/in³.
How to use this tool
- Enter density and from unit in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your kg/m³ and the full breakdown beneath it.
Formula
All densities are normalised to kg/m³, then converted to each output unit:
kg/m³ = value × factorfrom
Factors: 1 g/cm³ = 1,000 kg/m³, 1 g/mL = 1,000 kg/m³, 1 kg/L = 1,000 kg/m³, 1 lb/ft³ = 16.01846 kg/m³, 1 lb/in³ = 27,679.905 kg/m³.
How it works
The converter pivots on kg/m³, the SI unit of density. The input is multiplied by its kg/m³ equivalent to obtain a base value, then each output is produced by dividing that base by the corresponding output factor. Note that g/cm³, g/mL, and kg/L are all numerically equal to one another (all share the factor 1,000 kg/m³), so water's density of 1 g/cm³ = 1 g/mL = 1 kg/L = 1,000 kg/m³.
Common mistake: Confusing lb/ft³ with lb/in³. Because 1 ft = 12 in, one cubic foot is 12³ = 1,728 cubic inches, so 1 lb/in³ ≈ 1,728 lb/ft³. Mixing up these two units will produce density values that are off by nearly three orders of magnitude.
Worked example
Convert 1 g/cm³ to all density units
- Input: 1 g/cm³. Factor = 1,000 kg/m³.
- Base kg/m³ = 1 × 1,000 = 1,000 kg/m³.
- g/cm³ = 1,000 / 1,000 = 1; g/mL = 1,000 / 1,000 = 1; kg/L = 1,000 / 1,000 = 1.
- lb/ft³ = 1,000 / 16.01846 ≈ 62.428; lb/in³ = 1,000 / 27,679.905 ≈ 0.03613.
1 g/cm³ = 1,000 kg/m³ = 1 g/mL = 1 kg/L = 62.428 lb/ft³ = 0.03613 lb/in³.
Common mistakes to avoid
- Confusing g/cm3 with kg/m3 by a factor of 1,000 -- water is 1 g/cm3 = 1,000 kg/m3; entering 1 where 1,000 is needed is a very common unit-mix error in physics problems.
- Using density to calculate weight without specifying the volume -- density alone gives mass per unit volume; you need the object volume before you can find total mass.
- Mixing lb/ft3 and lb/in3 -- 1 lb/in3 = 1,728 lb/ft3 (since 1 ft3 = 12^3 = 1,728 in3); the numbers look similar but differ by over 1,000x.
Key terms
- Density
- Mass per unit volume, expressing how tightly matter is packed. The SI unit is kg/m³. Water at 4 °C has a density of exactly 1,000 kg/m³ (1 g/cm³).
- g/cm³ (grams per cubic centimetre)
- A common density unit in chemistry and materials science. Numerically identical to g/mL and kg/L. The density of water is 1.000 g/cm³ at 4 °C.
- lb/ft³ (pounds per cubic foot)
- A US customary density unit used in construction and HVAC. Air at sea level is about 0.0765 lb/ft³; concrete is roughly 150 lb/ft³.
- lb/in³ (pounds per cubic inch)
- A density unit used for dense materials such as metals. Steel is approximately 0.284 lb/in³. Because cubic inches are very small, this unit gives large-looking numbers for light materials.
Frequently asked questions
- What is the density of water in different units?
- Water at 4 degrees C: 1 g/cm3 = 1 g/mL = 1 kg/L = 1,000 kg/m3 = 62.428 lb/ft3 = 0.03613 lb/in3. These values are useful reference points for comparing other materials.
- How do I find if an object will float?
- Compare the object density to the fluid density. If the object is less dense than the fluid, it floats. For example, wood at about 600 kg/m3 floats on water (1,000 kg/m3), while iron at 7,874 kg/m3 sinks.
- Why does density change with temperature?
- Most materials expand when heated, increasing volume while mass stays constant, so density decreases. Water is a notable exception: it reaches maximum density at 4 degrees C and expands when either cooled to ice or warmed above 4 degrees C.