How to convert mass density units

The Density Unit Converter changes a value between six metric units of mass density: gram per cubic centimetre, kilogram per cubic centimetre, kilogram per cubic decimetre, gram per cubic metre, gram per cubic decimetre and kilogram per cubic metre. Type the number in the row of the unit you have — the other five rows fill with the equivalents as you type — and press Convert or Enter to have the status line report what was converted.

The conversion runs in this browser from the definitions below, so the page keeps working offline and nothing you type is uploaded. Results carry twelve significant digits, and a value that cannot be read leaves the other rows empty instead of showing the numbers of the previous run.

  1. Type the density in the row of its unit, for example 1 in the g/cm³ row. Decimals use a point — write 1.5, not 1,5 — and thousands separators such as 1,000 are not accepted.
  2. The other five rows fill while you type. Press Convert or Enter to hear the result: the status line names the value and the unit that were converted.
  3. Two pairs of rows are the same size: 1 g/cm³ is exactly 1 kg/dm³, and 1 g/dm³ is exactly 1 kg/m³. A 1 next to a 1 in those rows is correct, not a rounding error.
  4. Press Reset all to empty the six fields and the status line, or type over a result you no longer need.

Definitions, rounding and limits

The six units and their definitions

Every row converts through kilograms per cubic metre, the SI derived unit of density, so each unit is one fixed number: 1 g/cm³ = 1e-3 kg ÷ 1e-6 m³ = 1000 kg/m³, 1 kg/cm³ = 1e6 kg/m³, 1 kg/dm³ = 1 kg/L = 1000 kg/m³, 1 g/dm³ = 1 g/L = 1 kg/m³ and 1 g/m³ = 1e-3 kg/m³. The kg/m³ row is the base unit itself and reads back unchanged.

One litre is one cubic decimetre, so kg/dm³ is the same unit as kg/L and g/dm³ the same as g/L; a density quoted in g/mL is the same number as in g/cm³. Water at 4 °C is about 1 g/cm³, which is 1000 kg/m³ — the reason both values appear side by side in reference tables.

Rounding, input and the status line

Results carry twelve significant digits and are written as plain decimals between 1e-6 and 1e12 and in exponent notation outside that window, so 1 kg/m³ reads 0.000001 kg/cm³ and 0.001 g/cm³ rather than a long row of binary noise.

A comma is refused with an explanation instead of being deleted: half the languages this page is served in use it as the decimal mark, and the earlier filter turned 1,5 into 15 without a word. Exponent notation such as 1e3 is accepted, a negative value keeps its sign, and the status line under the table reports the row that was converted.

What this converter does not do

It converts units of mass density only. Thickness, area density and basis weight are different quantities, and the tool does not turn a density into a mass or a volume: that also needs the volume of the body, because 1 m³ of a material is not its density.

No reference densities are built in either. A value that has to come from a standard — the density of water at a given temperature, or of a particular alloy — has to be looked up elsewhere. The arithmetic here is exact for the definitions above, but the measurement it started from is only as good as its source.

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