File ConversionUnit ConversionFree Tool
Fuel Efficiency
Convert fuel efficiency between L/100km, km/L, MPG (US), and MPG (UK) — correctly handling the inverse relationship between distance-per-fuel and fuel-per-distance units.
How to Use Fuel Efficiency
- 1Enter the value to convert
- 2Select the source unit
- 3Select the target unit
- 4See the instant result
Frequently Asked Questions
L/100km measures fuel consumed per distance, while MPG and km/L measure distance covered per fuel unit — these are inverse (reciprocal) relationships, not a simple multiply-by-constant conversion like most units. This tool correctly handles that reciprocal math rather than treating fuel efficiency as a linear unit.
US and UK (Imperial) gallons are genuinely different volumes (1 US gallon ≈ 3.785 L vs. 1 Imperial gallon ≈ 4.546 L), so the same MPG number means a meaningfully different real fuel efficiency depending on which gallon is meant — mixing them up is a common real-world confusion this tool avoids by keeping them separate.
Based on precise gallon-to-liter and mile-to-kilometer conversion constants, with results shown to 6 decimal places.
No — the calculation happens entirely in your browser.
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