# How many water bottles make a gallon? | how many bottles of water make a gallon?

The conversion between any unit of volume, between the English gallon and the liter, between the cubic meter and the cup, is a constant conversion factor. So, if you have two units, Unit_A and Unit_B of volume, there will be a fixed conversion constant that relates them.

Unit_A = conversion_constant x Unit_B

So, for example, if Unit_A is a gallon and Unit_B is a quart, then

1 gallon = 4 x quart, and 4 is the conversion factor

Similarly,

1 liter = 1000 x milliliter, and 1000 is the conversion factor

If you need to find the equivalent amount of some multiple of Unit_A, you just multiply both sides of the equation. For example:

(5 x UnitA) = 5 x (conversion_contant x Unit_B)

Your specific problem is dealing with a conversion between a gallon and a volume unit of bottles, so your equation is:

1 gallon = conversion_unit x bottle_volume

If your bottle is a1-pint bottle equal to 16 ounces), you would enter 1 in the input side with “liquid gallon (US) ” shown as units.

Then select the pint unit on the output side.

8 pints is equivalent to 1 gallon.

For example, the “bottle unit” sometimes seen of 18 ounces. Your bottle becomes a standard unit itself.

You have to figure out the conversion constant for “bottle_units” :

1 gallon = conversion_constant x bottle_unit

That conversion for an 18 ounce bottle is as follows:

1 gallon = 128 ounces = conversion_constant x 18 ounces

which you turn into [ conversion_constant = 128 ounces / 18 ounces ] by dividing both sides of the equation by 18 ounces.

So, the conversion constant between 1 gallon and 18 ounce bottles is:

conversion-constant = 128 ounces / 18 ounces = 128/18