To determine how many bottles of water equal a gallon, you need to know the size of the water bottles you are referring to. The most common bottled water size is 16.9 fluid ounces (500 milliliters).

Conversion:

• 1 gallon = 128 fluid ounces
• 1 standard water bottle = 16.9 fluid ounces

Calculation:

Number of bottles per gallon = 128 fl oz ÷ 16.9 fl oz ≈ 7.57 bottles

Conclusion:

It takes about 7.5 bottles of 16.9 fl oz water to make one gallon. If your water bottles are a different size, just divide 128 by the bottle size in fluid ounces to get the number of bottles per gallon.