Being dimensionless, its unit is 1; it is expressed as a number, e.g., 0.18 or 18%.
Volume fraction is also called volume concentration in ideal solutions where the volumes of the constituents are additive (the volume of the solution is equal to the sum of the volumes of its ingredients).
The sum of all volume fractions of a mixture is equal to 1:
- For non-ideal mixtures, see Partial molar volume and Excess molar quantity.
- For alcoholic beverages, see alcohol by volume and Volume percent.