15 liters is how many gallons?

15 liters is 3.96 US gallons. It is 3.30 imperial gallons. The word “gallon” on its own is ambiguous, so the rest of this note separates the two.

US gallon

A US liquid gallon is 3.785411784 liters. Divide liters by that number. 15 ÷ 3.785411784 = 3.9626, which rounds to 3.96 gallons. Fuel pumps, US recipes, and most online converters use this gallon.

Imperial gallon

An imperial gallon, still seen in older UK references, is 4.54609 liters. 15 ÷ 4.54609 = 3.30 gallons. It is larger than the US gallon, so the same 15 liters fills fewer of them.

Check another amount

The liters to gallons converter starts at 15 liters and uses US gallons. Change the number for any other volume. For a smaller kitchen measure, US fluid ounces and milliliters are on the ml to oz page.