How do I convert % alcohol to the old British ° proof ?!
How do I convert % alcohol to the old British ° proof ?
Brought up with the old measure, can't get used to this Johnnie foreigner way of looking at booze...
Additional Details2 days ago
Cheers Prof. that explains the headaches, sooo, the 47% Mistra the farmer up the road has just dropped by.... OOoohhhh..
2 days ago
Thanks Edward..
Answers: 2 days ago
Cheers Prof. that explains the headaches, sooo, the 47% Mistra the farmer up the road has just dropped by.... OOoohhhh..2 days ago
Thanks Edward.. Prof is right, on the whole, but just for detail's sake, here's the reasoning behind it:
When the British Navy used to give a rum ration, every warship in the royal fleet had big barrels of the stuff on board stored in the mainbrace (hence - "splice the mainbrace" - ie, crack open the rum).
It was very important that if any of this rum was spilled, then it didn't stop the gunpowder from burning, so all the rum on a boat had to be 'proofed.' 100° (degrees) proof signified that the alcohol level in the liquor was high enough for the gunpowder to still burn if soaked. The percentage of alcohol in water required to allow this is 53% abv (hence the term "navy strength" for 53% or 'over-proof' spirits).
As spirits are now made to a particular abv, rather than proof, the approximation is that degrees proof is double the abv, as Prof mentioned, but you will find a very small discrepancy with the stronger spirits.
Hope this helps. Source(s):
I am a qualified and experienced professional sommelier.
Please see my profile. Times by two - eg 40% alcohol is 80 percent proof Sorry, I'm going to disagree.
Proof equalling double the alcohol by percentage refers to American proof, not British.
In Britain, -100 degree proof equals 57.15% alcohol by volume, a ratio of 7:4
Thus at the time of changeover from proof to abv the labels of whisky & gin showed 70 proof / 40% abv (whereas the same bottle labelled for the USA would be 80 proof)
So if you know the % abv, multiply that by 7 and divide by 4 to get proof -- thus your 47% abv drink is 82.25 proof.
Personally I think abv is a much easier to understand system of measurement than proof -- as has already been demonstrated :)