Volume Conversion Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/5/2026
To convert a volume, it's brought to a common unit (the liter) and then converted into the new unit. For example, 1 US gallon is about 3.785 liters.
Explanation
The liter is the volume unit of the metric system. The gallon, used in the United States and the United Kingdom, exists in two different versions that shouldn't be confused: the US gallon (3.785411784 liters), used notably for gas prices in the United States, and the UK imperial gallon (4.54609 liters), about 20% larger, used in the United Kingdom and some Commonwealth countries. Mixing up the two gallons is a common mistake that significantly skews a result. This calculator clearly distinguishes them to avoid this confusion. For a length conversion, see our length conversion calculator; for a weight, our weight conversion calculator.
Example: converting 1 US gallon to liters
Inputs
Value: 1. Starting unit: US gallon. Target unit: liters.
Calculation
1 US gallon × 3.785411784 liters per US gallon = 3.785411784 liters.
Result
1 US gallon is about 3.785 liters.
Frequently asked questions
Why are there two different gallon sizes?
The UK imperial gallon and the US gallon diverged historically: the United Kingdom redefined its gallon in 1824, while the United States kept an older definition derived from the English wine gallon. As a result, today the imperial gallon (4.546 L) is about 20% larger than the US gallon (3.785 L).
Does this calculator convert kitchen units like cups or spoons?
No, this calculator is limited to standard volume units (liter, milliliter, gallons). For cups, tablespoons, and teaspoons used in cooking, our kitchen measurement conversion calculator is better suited, with its own nuances (metric cup versus US cup).
How do I know if a stated gallon is US or imperial?
The geographic context usually tells you: American sources (gas prices, US recipes) use the US gallon, while British sources or those from some Commonwealth countries use the imperial gallon. If in doubt, check the original source before choosing the unit in this calculator.