Gallons to Liters Calculator
Gallons are the go-to unit for fluid volumes in the US, but metric-rated equipment and international projects call for liters. This converter takes a US gallon value and returns the equivalent in liters and milliliters instantly.
Enter any positive gallon value and the calculator does the rest. Use it for coolant fills, transformer oil volumes, or any situation where you need metric equivalents.
Conversion Formula
liters = gallons × 3.78541
1 US gallon = 3.78541 liters
For milliliters, multiply liters by 1,000. For example, 5 gallons equals 18.927 liters, or 18,927 milliliters.
Frequently Asked Questions
How many liters are in one US gallon?
One US liquid gallon equals approximately 3.78541 liters. This is based on the US gallon definition of 231 cubic inches. The imperial gallon is larger at 4.54609 liters.
Why convert gallons to liters?
Liters are the standard volume unit in most countries and in scientific contexts. Converting gallons to liters is necessary when working with metric-rated equipment, referencing international specifications, or communicating volumes on projects that follow metric standards.
Is 1 gallon roughly 4 liters?
Close but not exact. One US gallon is 3.785 liters, which is about 5.7% less than 4 liters. For rough estimates this approximation works, but for precise work you should use the exact factor of 3.78541.