That depends on your fluid ounce and your gallon. 16 glasses Answer and Explanation. How Many 16 9 Oz Bottles Make A Gallon How To Discuss How many water bottles in a gallon. . For example if the typical bottled water is 169 ounces Oz in size then 757 water bottles fill up a gallon completely. For example if the typical bottled water is 169 ounces Oz in size then 757 water bottles fill up a gallon completely. A fluid ounce in the US is defined as a 1128th of a US gallon meaning that 128 169 757 bottles containing 169 US fluid ounces of water each will make up exactly 1 US gallon. A 1-liter bottle of water is approximately 338 ounces so nearly 38 water bottles fill up a gallon. Gallons to water bottles formula. How many 16oz bottles make a gallon A Gallon is a measuring unit which is used to measure liquids that are equal to eight pints. You need to have 757 water bottles to equal a gallon. 169 US fluid oun...