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MPG to L/100km Fuel Consumption Converter

Convert fuel economy between US MPG, UK Imperial MPG, and L/100km. Features an inverse conversion logic for accurate international vehicle comparisons.

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About

Comparing vehicle efficiency across international markets requires navigating different measurement standards. In the United States and the United Kingdom, efficiency is measured in Miles Per Gallon (MPG), representing distance per fixed fuel volume. Conversely, the metric system (Europe, Canada, Australia) uses Liters per 100 Kilometers (L/100km), representing fuel volume consumed over a fixed distance. This fundamental difference creates an inverse relationship: higher MPG is better, while lower L/100km is better. Furthermore, the UK Imperial gallon is approximately 20% larger than the US liquid gallon, causing significant discrepancies if not properly distinguished.

fuel efficiency mpg calculator liters per 100km car specs imperial mpg

Formulas

The conversion is non-linear because one unit measures distance and the other measures volume. The formulas utilize fixed constants derived from the conversion of miles to kilometers and gallons to liters.

{
L/100km = 235.215MPGUSL/100km = 282.481MPGUK

Note that as MPG approaches zero, L/100km approaches infinity.

Reference Data

Efficiency LevelUS MPGUK (Imp) MPGL/100kmVerdict
Hyper-Miling6072.13.9Excellent
Hybrid / Diesel5060.04.7Very Good
Modern Sedan3542.06.7Good
Average Crossover2530.09.4Average
SUV / Truck1821.613.1Poor
Heavy Duty1214.419.6Very Poor
Performance89.629.4Inefficient
Exotic56.047.0Extreme

Frequently Asked Questions

The UK uses the Imperial Gallon (approx. 4.546 liters), whereas the US uses the US Liquid Gallon (approx. 3.785 liters). Since the UK gallon contains more fuel, a car will travel further on one UK gallon than on one US gallon, resulting in a higher MPG figure roughly by a factor of 1.2.
Generally, anything below 8 L/100km is considered good for a gasoline car. Hybrids often achieve 4-5 L/100km. Values above 12 L/100km are typical for large SUVs or trucks and are considered less efficient.
Yes, the formulas are reversible. To find US MPG from L/100km, you divide 235.215 by the L/100km value.
No. This tool is strictly for liquid fuel combustion. MPGe (Miles Per Gallon equivalent) uses a conversion based on the energy content of 33.7 kWh of electricity being equal to one gallon of gasoline, which requires a different calculation method.