Volume relationships include the void ratio, the porosity, and the degree of saturation. The void ratio,
denoted e, is the ratio of the volume of voids to the volume of solids:
The degree of saturation, denoted S, is the ratio of the volume of water to the volume of voids. It is commonly expressed as a percentage:
S = Vw / Vv x 100%
If all the soil voids are filled with water and no undissolved air is present, the soil is said to be saturated.