Proof | British Proof | American Proof

The term proof is the label found in Alcoholic Beverage bottle which indicates alcohol by volume percentage in a drink . It is a measure of how much ethanol is in Alcoholic drink. In Nepal , alcoholic strength are measured as per the percentage of alcohol by volume . Pure water has 0% alcohol by volume , absolute alcohol have 100% alcohol by volume and if a drink says 40% alcohol by volume it have 40% ethanol and 60% water. If 37% alcohol by volume, it have 37% alcohol and rest water.

It was developed by gay lussac . The proof is found in label of drink and U.S proof and U.k proof are different. In U.S.A the actual alcohol content by volume is half whatever proof number used. Example, in the above figure it says 88 proof which in U.S proof we have to divide it by 2 so alcohol by volume percentage will be 88/2 = 44% alcohol by volume. 

Proof is ancient method of testing strength of of spirits to ensure they are not mixed with water. There are two stories of proof, some says the concept of proof come from British royal navy who in 18th century had to douse their gunpowder in rum as test. If the wet gunpowder dipped in Rum ignites ,it is said it was proof with alcohol content higher than 57% . Other stories says Rum needed to be proof so it would not spoil gunpowder when barrel broke down.

Similarly in U.K proof , to calculate percentage of alcohol multiply U.K proof with 4 and divide it by seven. Or we can multiply U.S proof with 7 and divide by 8 to get U.K proof.

  • U.k proof = USA proof * 7 and divide by 8.

  • U. k proof  * 4 and divide by 7 gives percentage of alcohol

  • U.S.A proof = % of alcohol * 2 

  • And u.s.a. proof / 2 = Alcohol percentage.

  • 40 % alcohol by volume = 40% ethanol and 60% water. 

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