I feel like it would be useful to know exactly how much alcohol is in a can or a bottle. Also why is alcohol the only thing measured in percentages and not sugar or caffeine or medicine?
Alcohol is mostly measured in percentage by volume. Volume is the main measurement unit for liquids and measured in liters or gallons/fluid ounces, if you’re American. For the sake of easier math I use liters here.
Measured by percentage, alcohol gives you a comparable indicator of how strong a liquor is, and thus how easily you can get drunk off it. For example, most whiskey has 40% alcohol by volume, and many wines have 12%. This tells you very quickly that (pure) whiskey will get you drunk more than three times as fast as wine. Beer has 6%, so wine will still get you drunk double as fast.
You can still calculate the amount of alcohol easily, if you want. A 700ml bottle of wine may have 12% alcohol by volume. That means it is 700ml * 0.12 = 84ml of alcohol. If a 700ml bottle of whiskey is 40% alcohol, you have 700ml * 0.4 = 280ml of alcohol in there.
As for why caffeine and medicine aren’t measured in this way, it’s probably because they don’t come in vastly different strengths and you don’t need to compare them.
Caffeine is also often measured in “percentages” (amount per volume - not actually percentages as the numbers would be too confusingly small), usually specified as “32 mg/100 ml”.
Sugar is commonly given as “g of sugar/100g” in the nutrition label. That’s just a different way of saying %.
I don’t know, but sugar is usually in “g / 100g” so technically in percentage
Where I live they do three in a table: relative to 100g, per serving, and % of the daily recommended contained in one serving.
An absolute value would only be of use if you always consume the whole container. If you drink a glass of wine or a shot of vodka you’d have to start calculating the amount of alcohol consumed either way, and having it in percent saves you the first part of that mental math.
Cocoa percentage in chocolate
X% of the cans volume tells you the exact amount. You can know with very simple math. The reason why is because historically, alcohol drinks are taxed based on the concentration, or percentage, of alcohol. Beer would be taxed at a lower rate than say whisky. It was all based on the percentage, or “proof”, of the beverage, not the actual amount. That way a small and large jug of whisky would be taxed at the same rate.
