What is the abbreviation for gallon?

The abbreviation for gallon is "gal." It is commonly used in the United States and other countries to denote a unit of measurement for volume. One gallon is equal to 128 fluid ounces or approximately 3.785 liters. Gallons are often used to measure liquids such as gasoline, milk, and water. The abbreviation "gal" is derived from the old French word "galon," which originally referred to a liquid measure.