Cask strength

Cask strength (also known as barrel proof/barrel strength) is a term used by whisky (sometimes spelt "whiskey" in Ireland and the United States) and rum producers to describe a whisky or rum that has not been substantially diluted after its storage in a cask for maturation. The level of alcohol-by-volume (ABV) strength for a cask strength whisky or rum is typically in the range of 52–66% ABV.^[1]

Most bottled whisky and rum is diluted with water to reduce its strength (i.e., ABV level) to a level that makes it less expensive to produce and more palatable to most consumers – usually 40% ABV, which is the legal minimum to still be classified as whisky/rum in most countries, including the United States, United Kingdom, and all EU member states (although this can be as low as 37% in Australia^[2] or as high as 43% in South Africa^[3]). The degree of dilution significantly affects the flavour and general drinking experience of the whisky or rum.