Additional Information Entries can be made in any of the boxes numbered 1 to 5 A single entry in [1,2 or 3] will produce equivalent values in the other two boxes (after Calculate It has been clicked). A single entry in [1,2 or 3] plus another entry in [4 OR 5] will produce answers in all the remaining boxes. Entries in BOTH [4 & 5] will get results in [1,2,3]. The types of measure given in the two drop down menus on the right may be altered at any time. The results will depend on the stage the calculation is at. Erroneous entries will be signalled at the top, and it will be necessary to click on Clear All to restart.
The significant figures option should not be needed (the default value of 3 is usually adequate for all this work) but is there *just in case*. Whatever the setting, unvalued zeros are not shown.
See also the Background Notes on Alcohol Content of Drinks.
There are calculators for finding the number of alcohol units contained in various sizes of measures either indifferent countries OR the UK ONLY There is a separate calculator for comparingEquivalent values of Unit Drinksin various countries. 

%AbV is the percentage of Alcohol by Volume
One obvious use of this calculator is to find how much alcohol there is in a particular quantity of drink. Knowing the %AbV (or proof) of the liquid and how much of it there is (in litres, pints, bottles etc.), it is only a matter of putting those two pieces of information in (making sure the units of the measure are correct) and clicking on [Calculate It] to get the answer at the bottom. The units of measurement for that can also be altered to suit.
For example. Seeing a bottle (75 cL) of wine with an AbV of 12%, we enter 12 in box 3 and 1 in box 5 select bottle(=75cL) for the units to find that the bottle contains 90 mL of alcohol. Or 71 grams or 2.5 ounces(avoir) and so on.
But there are other uses. It can be used to find the %AbV of a drink (to use in one of the other calculators) if the strength is given in some other way, like grams of alcohol in litres (or mL) of liquid. This information, put into boxes 4 & 5 respectively will give the %AbV (or proof) of the drink.
Other uses can no doubt be found.
Clearly an AbV of over 100% cannot exist. An attempt to put in, or produce, such a value will generate a warning message. 