Frequently Asked Questions
Gallons vs Liters: Two Systems, One World
The United States measures liquid volume in gallons, quarts, and ounces. The rest of the world uses liters and milliliters. You will encounter the conversion constantly when buying fuel abroad, comparing vehicle fuel economy across countries, reading imported product labels, or working with recipes and brewing instructions from non-U.S. sources.
Note that there are two types of gallon: the U.S. gallon (3.785 liters) and the Imperial gallon used in the UK and Canada (4.546 liters). This converter uses the U.S. gallon unless otherwise noted.
The Conversion Formula
- US gallons to liters: gallons × 3.78541
- Liters to US gallons: liters ÷ 3.78541
Fuel Economy: MPG vs L/100km
U.S. fuel economy is rated in miles per gallon (MPG). Most of the world uses liters per 100 kilometers (L/100km) — a lower number means more efficient. To convert: divide 235.2 by your MPG to get L/100km. A 30 MPG vehicle uses 7.84 L/100km.
| US Gallons | Liters | Context |
|---|---|---|
| 1 gallon | 3.785 L | Standard reference |
| 5 gallons | 18.93 L | Paint bucket size |
| 15 gallons | 56.78 L | Small car fuel tank |
| 150 gallons | 567.8 L | Typical semi truck tank |