Fuel Efficiency Converter
Convert fuel efficiency between MPG (US/UK), L/100km, and km/L for accurate vehicle comparison and trip planning
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Complete Guide: Fuel Efficiency Converter
Everything you need to know about using this tool effectively
The Fuel Efficiency Converter transforms fuel economy measurements between four units: MPG (US), MPG (UK), liters per 100 kilometers (L/100km), and kilometers per liter (km/L). Different countries use different units for fuel economy, and this tool lets you compare them. All processing happens in the browser.
This tool converts between fuel efficiency units using standard conversion factors. US MPG uses US gallons. UK MPG uses imperial gallons (1.20095 US gallons). L/100km is the inverse relationship to MPG. The tool handles all conversions bidirectionally.
Comparing US and European car fuel economy
Convert a European car's L/100km rating to US MPG to compare with American vehicles.
Evaluating rental cars abroad
Convert a rental car's L/100km rating to MPG to understand fuel costs.
Buying an imported vehicle
Convert a UK-spec car's MPG (UK) to US MPG for comparison with domestic models.
Calculating fuel costs
Convert fuel efficiency to L/100km to estimate fuel consumption for a trip distance.
Enter the fuel efficiency value
Type the value and select the source unit.
View all conversions
The tool shows the equivalent in all four units.
Use presets
Click a preset for common efficiency levels.
Copy a value
Copy the unit you need.
Higher MPG means better fuel economy. Lower L/100km means better fuel economy.
US MPG and UK MPG differ because UK gallons are 20% larger than US gallons.
To convert L/100km to US MPG: 235.21 / L/100km = US MPG.
A car that gets 30 US MPG uses about 7.84 L/100km.
What is the difference between US and UK MPG?
A UK imperial gallon is 1.20095 times larger than a US gallon. So a car rated at 40 MPG (UK) would be about 33.3 MPG (US).
Why does Europe use L/100km instead of MPG?
L/100km measures fuel consumption (lower is better), while MPG measures fuel economy (higher is better). The metric system uses consumption-based measurement, which some find more intuitive for calculating fuel costs.
Is my data sent to a server?
No. All conversion happens in your browser. Nothing is transmitted.
How do I convert L/100km to US MPG?
Divide 235.21 by the L/100km value. For example, 10 L/100km = 235.21 / 10 = 23.5 US MPG.
Can I compare electric vehicle efficiency?
This tool is for fuel vehicles. Electric vehicles use different efficiency units like kWh/100km or miles per kWh.