BCBetter Calculators

Gallons to Liters Calculator

Convert US gallons to liters instantly.

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Enter your values and click Calculate

How It Works

Liters = Gallons × 3.78541. The conversion factor 3.78541 is derived from the legal definition of the US liquid gallon as exactly 231 cubic inches, combined with the metric definition of a liter as exactly one cubic decimeter (1,000 cubic centimeters). Working through those unit relationships gives 1 US gallon = 3.785411784 liters exactly. The calculator uses the rounded constant 3.78541, which introduces less than 0.00003% error — negligible for any practical purpose. The UK imperial gallon is a different unit (4.54609 liters) and is not used by this calculator. Results are displayed to four decimal places to provide precision for small volumes; large volumes like pool capacities will return large whole-number results.

Examples

5-Gallon Jug
A standard 5-gallon water jug converted to liters.
Result: 5 gallons equals approximately 18.927 liters.
One Gallon of Milk
A common US milk jug size.
Result: 1 gallon equals approximately 3.785 liters.
Gas Tank
A 15-gallon car fuel tank in liters.
Result: 15 gallons equals approximately 56.781 liters.

Frequently Asked Questions

How many liters are in a gallon?
One US liquid gallon equals exactly 3.78541 liters.
Does this work for UK gallons?
No. This calculator uses the US gallon. The UK imperial gallon is larger — approximately 4.54609 liters.
How many liters is a half gallon?
Half a US gallon equals approximately 1.89271 liters.

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