Dilution Calculators

If you want to know how much water to add to dilute your alcohol down, just multiply the amount of spirits you have by (strong/weak) - 1

eg: if you want to dilute 2L of 75% alcohol down to 40%, you will need to add 2 x ((75/40)-1) = 1.75L of water
Dilute of % alcohol Down to %
By adding Water

If you want to know how much alcohol to use to make a known quantity, multiply the final amount by (weak/strong)

eg: to make 1.125L of 40% alcohol using spirit at 75%, you will need to use 1.125 x (40/75) = 0.6L of the 75% spirit, then top it up to 1.125L using water.
To make of % alcohol using % alcohol
Use of Alcohol    
and of Water

Proof or Abv ?

Note that there are a couple of different ways of describing the alcohol strength. Some people tend to talk about "Proof" whereas others (myself included) tend to stick to "ABV" - the amount of Alcohol By Volume. Basically 100 proof = 50% abv.

But its not always so ... Harry explains ...