What is a fuel economy converter?
Convert fuel economy among U.S. mpg, imperial mpg, kilometers per liter and liters per 100 kilometers with reciprocal-unit handling. It is designed for quick everyday and technical unit comparisons without requiring sign-up or server-side calculation.
How does this converter work?
The calculator converts the entered value through a common reference unit or an exact scale relationship, then converts that reference value to the selected target unit. Intermediate values are not rounded. This follows the general NIST approach of choosing an appropriate conversion factor, canceling units and rounding the final quantity rather than intermediate steps.
Which units are supported?
Miles per U.S. gallon, miles per imperial gallon, kilometers per liter and liters per 100 kilometers.
Use the unit labels carefully when similar names can represent different systems. The selected units are always shown again in the result panel.
How do you use this fuel economy converter?
- Enter the numerical value you want to convert.
- Select the starting unit.
- Select the target unit, or use Swap Units to reverse them.
- Keep precision on Automatic or choose a significant-digit setting.
- Select Convert, then review the conversion relationship and result details.
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For optional supporting equipment or reference material, you can browse Vehicle logbooks (paid link) on Amazon.com. Record actual mileage, fuel, charging or running costs before calculating. Check the vehicle documentation; record-keeping does not certify fitment or roadworthiness. No purchase is required to use this calculator.
Conversion example
30 U.S. mpg is approximately 7.8405 L/100 km. Because L/100 km is a consumption measure, lower numbers indicate less fuel used.
Accuracy, definitions and rounding
Fuel-economy conversion changes units only. It does not predict real-world vehicle efficiency, driving conditions, fuel cost or emissions.
For important engineering, scientific, commercial or regulatory work, confirm that the unit definition, measurement uncertainty and required significant digits match the standards used in your application.
Worked example: Fuel Economy Converter
Enter the following values in the Fuel Economy Converter and calculate to reproduce this result.
- Value to convert: 10
- From unit: Miles per U.S. gallon (mpg US)
- To unit: Miles per imperial gallon (mpg Imp)
- Displayed precision: Automatic
Example result: 12.009499255 mpg Imp. 10 Miles per U.S. gallon (mpg US) equals 12.009499255 Miles per imperial gallon (mpg Imp).
Calculation used: 10 mpg-us → 12.009499255 mpg-imp
How to interpret this example
A U.S. gallon and an imperial gallon are different volumes, so mpg values differ even for the same vehicle. Confirm which gallon the source uses. Fuel-consumption units such as L/100 km vary inversely with mpg rather than by one fixed multiplier.
Frequently asked questions
Sources and methodology
The calculation relationships and explanatory notes are based on authoritative measurement references. Links open the original source so you can verify the unit definitions and conversion guidance.