There are 128 ounces in a gallon. A gallon is a unit of volume that is commonly used to measure liquids, such as water and milk. One gallon is equal to 128 fluid ounces, or 16 cups, or 8 pints.

The gallon is a standard unit of measurement in the United States and is also used in some other countries, such as the United Kingdom and Canada. In the metric system, the equivalent unit of measurement for a gallon is the liter, which is slightly smaller than a gallon. One liter is equal to approximately 0.26 gallons, or 33.8 fluid ounces.

To convert gallons to ounces, you can use the following formula: number of ounces = number of gallons x 128. For example, if you have 3 gallons of water, you can multiply 3 by 128 to find that you have 384 ounces of water.

It is important to note that there are different types of gallons, such as the liquid gallon and the dry gallon. The liquid gallon is used to measure liquids, while the dry gallon is used to measure dry goods, such as grains and flour. The number of ounces in a dry gallon is slightly different from the number of ounces in a liquid gallon, so it is important to use the correct conversion factor when converting between these units of measurement.