The concept of Cask Strength entails that the whisky has been extracted from the cask without any dilution by water prior to bottling. When whisky is first introduced into the cask, its alcohol content typically reaches approximately 63%, and this potency can persist when it is chosen for bottling. To cater to the preferences of the general imbibers, most conventional whisky releases undergo a process of dilution with water to reduce the alcohol content (commonly to around 43% or 46% in SA). Consequently, cask strength whiskies do not hold widespread appeal among the average drinkers.

In certain instances, a whisky may possess a higher alcohol strength without explicitly being labeled as cask strength. These heightened strength releases are also included here for consideration. (In the United States, the corresponding term for cask strength is “barrel proof.”)