There is 128 ounces in a. gallon. and 8 ounces in a. cup. so you would have 16. cups. in a. gallon. !
http://wiki.answers.com/Q/How_many_cups_water_equa...

There are 16 US cups in one US gallon. To convert a value in US gallons to US cups, multiply by 16. Also, 1 Imperial Gallon equals 19.215 US cups.
http://www.kgbanswers.com/howmanycupsofwatere...

One cup = 8 Ounces. One gallon = 128 Ounces. 128/8 = 16 Cups/gallon, 8 Pints/gallon, 4 quarts/gallon. : Hope this helps! :
http://answers.yahoo.com/question/index?qid=200607...

Hi Jessica, Very close to 19 cups. Sorry to convert to metric: 1 gallon equals 3785.4 c"c. A cup is around 200 c"c..... 3,785.4 : 200 is just short of 19. Please note
http://aolanswers.com/questions/measuring_73561913...
