Volume fraction

Volume fraction is the volume of one constituent divided by the total volume of a mixture or multiphase material. Fractions of all constituents sum to one when they partition the total volume.

Volume: Volume measures the three-dimensional space occupied by a region or object. It supplies the numerator and denominator in the defining ratio.
Volume percent: Volume percent is a volume fraction multiplied by 100. It reports the same composition ratio on a percentage scale.
Additive volume: Additive volume is the assumption that a mixture's volume equals the sum of its constituent volumes. When volumes are nonadditive, the denominator needs an explicit mixture-volume definition.
Mass concentration: Mass concentration is the mass of a constituent per unit volume of a mixture. Unlike volume fraction, it has units and uses constituent mass in the numerator.
Mixture: A mixture is a physical combination of substances that retain their chemical identities. Its total volume provides the reference for constituent fractions.
Volume of distribution: Volume of distribution is a pharmacokinetic parameter relating the amount of drug in the body to its plasma concentration. The parameter is a volume ratio, though not a literal anatomical volume fraction.
Partial molar volume: Partial molar volume is the change in a mixture's volume when a component's amount changes at fixed conditions. It accounts for interactions that make component volumes differ from pure-component volumes.
Molar concentration: Molar concentration is the amount of a substance in moles per unit volume of solution. It measures amount per volume rather than a dimensionless share of total volume.
Mass fraction: Mass fraction is a constituent's mass divided by the total mass of a mixture. It measures composition by mass rather than by volume.
Particle packing: Particle packing describes how solid particles occupy space within a bed or assembly. The solids volume fraction determines how much of a packed bed is particle material.

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Parts-per notationRelated: Gas mixtures and solutions may report parts-per values based on volume.