Fuel Consumption Converter - MPG, L/100km, km/L

Fuel Consumption Converter — MPG, L/100 km, km/L

Fuel economy can be expressed as distance per volume (miles per gallon, kilometers per liter) or as volume per distance (liters per 100 kilometers, gallons per 100 miles). This tool converts between common automotive units using standard definitions: the international mile (1.609344 km), the US liquid gallon (3.785411784 L), and the UK imperial gallon (4.54609 L).

Supported units

Liters per 100 km (L/100 km) — common in Europe; lower is better.
Kilometers per liter (km/L) — common in Asia; higher is better.
Miles per US gallon and miles per UK gallon — higher is better; do not mix US and UK gallons.
US or UK gallons per 100 miles — fleet-style consumption figures.
Liters per meter (L/m) — rarely used; included for completeness.

Why US and UK MPG differ

A UK gallon is larger than a US gallon. The same car therefore shows a higher MPG figure in UK units than in US units even when the underlying efficiency is identical. Always label which gallon definition you use in reports and dashboards.

Limits

Results are for quick engineering and consumer comparisons. Regulatory fuel economy labels, taxation, and emissions reporting may use additional correction factors not modeled here.

Frequently Asked Questions

Is lower L/100 km better?

Yes. L/100 km is fuel per distance, so a smaller number means you burn less fuel to travel the same distance.

How do I convert 30 MPG US to L/100 km?

Select miles per US gallon as the source unit, enter 30, then choose liters per 100 km as the target. The tool normalizes through L/100 km internally.

Can I swap source and target units?

Use the Swap button to exchange the two unit dropdowns while keeping the numeric value in the left field.

Why does km/L need a positive value?

km/L divides into the conversion; zero or negative values are not meaningful for fuel economy, so the tool treats them as invalid.