The rough answer is "about 0.5 liters make a pint", but it depends how accurate you need to get. There are slightly different sizes of "pint" (and therefore quart and gallon) in different countries. For example, the British ("imperial") pint is 0.568l, and a US pint is 0.473l. Double those two quantities and you'll get something close to a liter. If it's water, you probably won't care much which kind of pint you get. If it's Chanel No. 5 then you might care. :)