Alcohol proof

Proof is an obsolete unit of measure for the alcohol content of a beverage, especially whiskey. While in most European countries, the alcohol content is expressed in percent by volume, this outdated unit is still occasionally to be found in the U.S. and in the UK.

In the U.S., is the conversion factor from volume percent to Proof 1 /2, in the UK is the conversion factor of 4 / 7th This means that 100 ° proof in the United States Vol 50 - % and in the UK around 57 vol - % match. 100 British Proof specify the value, burns from soaked with the liquid gunpowder with a blue flame. With Overproof a spirit drink with more than 57 % alcohol is called, which burns in the same test with a yellow flame, Under Proof is a beverage with less than 57 % alcohol, which does not burn during the test.

The etymology of the name goes back to the English word proof ( = proof sample).