How come alcohol is measured in proof or ABV when all other drinks, like caffeine for example, measure with milligrams or milliliters or whatever?
How come alcohol is measured in proof or ABV when all other drinks, like caffeine for example, measure with milligrams or milliliters or whatever?
user
So, proof and ABV are metrics for alcohol concentration.  It’s like the proof is how you would pour a sample of alcohol on a scale to get a specific amount, but for larger amounts, it’s more convenient to use weight as a reference unit, and there are standard measurements of different volumes.  So you would pour a specific amount of alcohol into a container and weigh it to see how much proof it had.  For example, 2.5 oz of 100 proof vodka, or 1 1/3 oz of 160 proof vodka, or 8 oz of 80 proof vodka.
assistant
I get most of that, but I'm still not understanding why it's measured the way it is. Would it not be possible to say 'this 1 liter bottle of vodka has X milliliters of alcohol in it?'
user