Gallons to Liters (Litres) Converter: US and Imperial Gallons

US gallons, imperial gallons and liters

A US liquid gallon is defined as 231 cubic inches, which works out to exactly 3.785411784 liters. To convert US gallons to liters, multiply by 3.7854. To convert liters to US gallons, divide by 3.7854, or multiply by 0.26417. Worked example: 10 US gallons is 37.85 liters. A standard 5 gallon water jug is 18.93 liters, and a 15 gallon gas tank is 56.78 liters.

The imperial gallon used in the United Kingdom is a different unit. It is defined as exactly 4.54609 liters, about 20 percent larger than the US gallon. That is why a car advertised at 40 miles per imperial gallon is only about 33 miles per US gallon. When you read fuel economy, tank size or paint coverage from a foreign source, check which gallon it uses before converting. The page shows both side by side to avoid the trap.

The spelling liter (US) and litre (elsewhere) mean the same thing: 1,000 cubic centimeters. Travelers meet this on rental cars, camping fuel and bottled water, and the ounces to mL converter covers the small end. For a road trip budget, combine it with the miles to km converter. For a motorhome trip, see the RV trip cost calculator, where fuel dominates the budget. It also helps with boat fuel, aquarium water changes, camping stove fuel and pool chemicals, all of which are sold in gallons in one country and liters in another.

Reference table of common volumes, plain HTML so it works without JavaScript.

Where these numbers come from

The formulas and default values in this calculator are based on:

• NIST SP 811 Appendix B8, conversion factors (nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8) (US liquid gallon and exact imperial gallon of 4.54609 L)
• NIST unit conversion guidance (nist.gov/pml/owm/metric-si/unit-conversion). Note: US gallon equals 231 cubic inches, so 3.785411784 L

This is a planning estimate, not medical, legal or immigration advice. Fees, allowances, limits and entry rules change, so confirm the figures with your airline, cruise line, customs agency or the official government source before you book or travel, and follow their rules if they differ from this page.