Gallons to Liters Converter
Convert US gallons to liters instantly.
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Convert gallons to liters
Key in a gallon figure and the liter total appears at once, with the reverse also live. One US gallon equals 3.785412 liters, so multiplying gallons by that figure gives liters. It is handy for fuel economy, tank capacities and recipes when moving from US units to metric. The calculation never leaves your browser.
Quick reference
1 gal = 3.785412 L, 5 gal is about 18.93 L, and 20 gal is roughly 75.71 liters.
US gallons, liters, and the conversion factor
This converter uses the US liquid gallon. It does not treat an Imperial gallon as the same unit.
Method
Multiply US liquid gallons by 3.785411784 to obtain liters. Entering liters uses the inverse operation.
liters = US gallons x 3.785411784
Worked example
Five US gallons equal 18.92705892 liters, which is about 18.9271 liters when rounded to four decimal places.
Limits
- An Imperial gallon equals 4.54609 liters, so confirm which gallon your source uses.
- The conversion factor is more precise than most measuring containers.
- A converted number does not add accuracy to the original measurement.
- NIST Guide to the SI, conversion factors: US and Imperial gallon-to-liter factors.
Reviewed against the current calculator or processor on September 6, 2026.
Frequently asked questions
How many liters is a gallon?
One US gallon equals 3.785412 liters. To convert, multiply the number of gallons by 3.785412.
Is this US or UK gallons?
This converter uses US gallons at 3.785412 liters each. A UK (imperial) gallon is larger, about 4.546 liters.