Free Online Gallons to Liters

Gallons to litres depends on region: 1 US gallon = 3.78541 L, 1 UK Imperial gallon = 4.54609 L exactly. Toggle the region.

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1 US gallon = 3.785411784 L. UK gallon is 20% larger than US.

How to Use This Converter

  1. Toggle the region between US gallon and UK Imperial gallon.
  2. Type a value into either the Gallons or Litres field.
  3. The other field updates instantly using the chosen factor.

What Is a Gallons to Liters?

The US gallon and the UK Imperial gallon differ by roughly 20%. The US gallon is exactly 3.785411784 L (defined via 231 cubic inches). The UK Imperial gallon is exactly 4.54609 L (defined in the Weights and Measures Act 1985). The same number on a fuel-economy spec sheet means different things on either side of the Atlantic.

US drivers planning a Canadian or UK trip, expats reconciling a US car's tank against European pump prices and brewers comparing US and UK gallon batch sizes all flip between the two. The UK still informally uses gallons for fuel pricing even though pumps dispense in litres; the US uses them everywhere from the pump to the milk jug.

Toggle the region in the tool and the factor swaps; both directions remain two-way.

Frequently Asked Questions

US vs UK gallon?
1 US gallon = 3.785 L. 1 UK gallon = 4.546 L. UK gallon is 20% larger.
Gas mileage conversion?
US mpg to km/L: multiply by 0.425. 30 mpg = 12.75 km/L.
How many liters in a gallon?
US: 3.785 L. UK: 4.546 L. Specify which gallon for accuracy.

Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.

Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.

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