Mass per volume, with a defined basis
Density is mass per unit volume. It lets a supplied material measurement be expressed in kg/m³, g/cm³, g/mL or lb/ft³. It is useful when comparing material data sheets or preparing a mass-volume calculation. It does not identify a substance or supply a reliable density for an unknown material.
One g/cm³ equals 1,000 kg/m³ because both the mass prefix and the cubed length denominator change. One g/mL is the same density as one g/cm³, since 1 mL = 1 cm³. Material density can depend on temperature, pressure, porosity and the definition of bulk volume; those conditions are not removed by a unit conversion.
Mass is density multiplied by volume when the density describes the material and conditions being considered. One g/cm³ equals 1,000 kg/m³, and one litre is 0.001 m³. Bulk powder density can include voids and packing, while a material’s true density uses a different volume basis. A unit conversion cannot make those density definitions interchangeable.
Use the supplied density at the relevant temperature and convert the volume to a compatible cubic unit before multiplying.
The density must match the material and volume basis
A supplier gives a liquid density in g/cm³ and a container volume in litres. The mass estimate needs those values to speak the same dimensional language. Density is not a universal label for a substance: its measurement conditions, temperature and composition can affect the value you should use.
Using an illustrative density of 0.8 g/cm³, a 2 L liquid volume has mass 1.6 kg. Convert the density to 800 kg/m³ and the volume to 0.002 m³, then multiply. Converting the volume into millilitres instead gives 2,000 cm³, so 0.8 × 2,000 = 1,600 g. Both routes describe the same assumed mass.
Density measured at one temperature may not apply at another. Liquids can expand while retaining nearly the same mass, and mixtures can have different densities from their components. Use a measured or documented value appropriate to the composition and conditions. The example density is deliberately unnamed; it is not a lookup value for a particular product.
Bulk density for a powder includes the chosen packing arrangement and can include voids between particles. True material density refers to a different volume basis. Using one in place of the other can distort a container or transport estimate even when the units match perfectly. Record whether the sample is loose, tapped or otherwise prepared, and keep the source's method beside the converted number.
800 kg/m³ × 0.002 m³ = 1.6 kg.
0.8 g/cm³ in kilograms/cubic metre
0.8 g/cm³ = 800 kg/m³
Output = input × source factor ÷ destination factor0.8 × 1,000 ÷ 1 = 800 kg/m³. The two factors express the source and destination relative to the same internal reference unit. Their ratio is the multiplier.
Both unit factors refer to the same internal reference for density. Multiplying by the source factor and dividing by the destination factor changes the numerical scale while retaining the quantity. The source definition still matters: The cubic volume denominator must also be converted. Use the complete density unit.
Reversing the unrounded 800 kg/m³ result returns 0.8 g/cm³. Use this as a direction check. A consistent reverse calculation cannot resolve converting only the mass numerator or improve the original observation.
What this density comparison can tell you
Useful capabilities
Use the supplied density at the relevant temperature and convert the volume to a compatible cubic unit before multiplying.
The listed units express the same supplied density quantity. The 0.8 g/cm³ → 800 kg/m³ example makes the selected convention visible before it is used in a longer calculation.
Important limits
Density is mass divided by volume. Real material density changes with temperature and pressure.
The cubic volume denominator must also be converted. Use the complete density unit. Specific gravity is a ratio to a reference density. Its conversion requires that reference and its conditions.
| Possible mismatch | What resolves it |
|---|---|
| Converting only the mass numerator | The cubic volume denominator must also be converted. Use the complete density unit. |
| Treating specific gravity as a density unit | Specific gravity is a ratio to a reference density. Its conversion requires that reference and its conditions. |
Temperature, composition and preparation can affect density more than the unit display. A loose powder and a compacted powder may use different bulk-volume bases. For a mass estimate, both density and volume carry measurement uncertainty. Retain the source temperature and material definition rather than assuming that one converted density describes every sample or packing arrangement.
As a controlled uncertainty example, suppose the original 0.8 g/cm³ record had a stated ±1% input interval. Its endpoints would be 0.792 g/cm³ and 0.808 g/cm³. Converting those endpoints gives an output interval from 792 kg/m³ to 808 kg/m³. The interval scales with the same fixed unit ratio as the central value. This chosen interval illustrates the arithmetic and is not an accuracy claim for your measurement.
Density units, side by side
The values below all describe 0.8 g/cm³. They provide a comparison of unit sizes for density; they are not separate measurements. Read the complete symbol and convention before copying a number.
| Unit | Symbol | Equivalent |
|---|---|---|
| Kilograms/cubic metre | kg/m³ | 800 kg/m³ |
| Grams/cubic centimetre | g/cm³ | 0.8 g/cm³ |
| Grams/millilitre | g/mL | 0.8 g/mL |
| Pounds/cubic foot | lb/ft³ | 49.9423684609 lb/ft³ |
Keep the original grams/cubic centimetre record alongside the converted kilograms/cubic metre display. The unit list uses up to twelve significant digits for arithmetic readability, while the measurement precision still comes from its source.
Use the density for the actual conditions
For a liquid shipment estimate, use the supplier’s density at the stated temperature, convert it to kg/m³ and express the liquid volume in m³ before multiplying. Record both source values.
The following inputs stay in grams/cubic centimetre and the results use kilograms/cubic metre. They illustrate different magnitudes for this measurement. Retain the specific conditions described above when replacing an example with your own value.
| Starting value | Equivalent value |
|---|---|
| 0.8 g/cm³ | 800 kg/m³ |
| 1 g/cm³ | 1,000 kg/m³ |
This density unit pair has a constant factor ratio. Changing the input changes the output by the same proportion. If a copied figure differs by an unexpected factor, review the full unit symbol before changing the source measurement. Specific gravity is a ratio to a reference density. Its conversion requires that reference and its conditions.
Use the supplied density at the relevant temperature and convert the volume to a compatible cubic unit before multiplying.
Questions about density
Are g/mL and g/cm³ the same?
Yes. A millilitre is a cubic centimetre, so the same numerical value applies in those two density units. That equivalence does not imply every substance has a density of 1 g/mL.
Can this turn litres into kilograms?
The density converter alone does not calculate that mass. Convert the supplied density and volume to compatible units, then multiply density by volume. The density must describe the actual material.
Before using this density result
- Use a density measured for the relevant material, temperature and pressure.
- Distinguish bulk, apparent and true density in porous materials and powders.
- Keep mass and volume units compatible when applying m = ρV.
Keep the original density value, its unit and the relevant conditions in the record. A copied answer of 800 kg/m³ is interpretable only when those details remain available. State which of the measurement checks above you verified before using the value in another calculation.