Fuel Economy Converter
Convert between miles per gallon, kilometers per liter, and liters per 100km.
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This converter handles fuel economy across the units used in different countries â miles per gallon (mpg), kilometers per liter (km/L), and liters per 100 kilometers (L/100km) â converting your value to kilometers per liter (the base unit) first.
MPG and km/L both measure distance traveled per unit of fuel consumed, so a higher number means better efficiency in both â this matches the common intuition that "more miles per gallon is better." These two units convert directly: 1 mpg (US) â 0.4251 km/L, using the standard US gallon and mile definitions.
L/100km flips the relationship around, measuring fuel consumed per fixed distance traveled instead â so for this unit, a LOWER number means better efficiency, since it means less fuel was needed to cover the same 100 km. Because the units are inverted, converting between L/100km and the other two requires a reciprocal formula rather than a simple multiplication factor.
This inversion is exactly why a direct linear conversion doesn't work between L/100km and mpg/km-per-liter â going from km/L to L/100km, for example, requires dividing 100 by the km/L figure (100 Ă· km/L = L/100km), reflecting that one measures "distance per fuel" and the other measures "fuel per distance."
Regional convention explains why different units dominate in different places: the US and UK commonly use miles per gallon (though US and UK/imperial gallons differ slightly in size, which is a separate common point of confusion), continental Europe commonly uses L/100km, and many other countries use km/L or L/100km interchangeably depending on local convention.
For context, a typical modern gasoline sedan might get roughly 30-40 mpg (about 12.75-17 km/L, or 5.9-7.8 L/100km), while a large SUV or truck might get roughly 15-20 mpg (about 6.4-8.5 km/L, or 11.75-15.7 L/100km) â useful benchmarks for sanity-checking a converted fuel economy value.
Electric vehicles complicate fuel economy comparisons further, since they consume electricity rather than liquid fuel â their efficiency is typically expressed in different units entirely (like miles per kWh or kWh per 100 km), sometimes with an "MPGe" (miles per gallon equivalent) figure used for rough cross-comparison against gasoline vehicles, based on the energy content of a gallon of gasoline.
Why is L/100km different from the others?
MPG and km/L measure distance per unit of fuel, while L/100km measures fuel per unit of distance â so a lower L/100km means better efficiency, unlike the other units.
Why does a lower L/100km number mean better fuel economy?
L/100km measures fuel consumed to travel a fixed distance, so needing less fuel for the same 100 km directly means better efficiency â the opposite relationship from mpg or km/L.
How do I convert L/100km to km/L?
Divide 100 by the L/100km value â for example, 8 L/100km converts to 100 Ă· 8 = 12.5 km/L.
Why can't I just multiply to convert between mpg and L/100km?
Because the two units measure inverse relationships (distance-per-fuel vs. fuel-per-distance) â converting requires a reciprocal (division-based) formula, not a simple multiplication factor.
Are US and UK gallons the same size?
No â a US gallon (3.785 liters) is smaller than a UK/imperial gallon (4.546 liters), so mpg figures quoted in the US and UK aren't directly comparable without accounting for this difference.
What's a typical fuel economy for a modern sedan?
Roughly 30-40 mpg, which is about 12.75-17 km/L or 5.9-7.8 L/100km, though this varies by specific vehicle, engine, and driving conditions.
Which fuel economy unit is used in Europe?
L/100km (liters per 100 kilometers) is the standard convention across most of continental Europe.
Does this calculator account for the difference between US and imperial gallons?
Yes â check which gallon definition your source figure uses, since US and imperial gallons differ in size and this affects the mpg conversion.
How is electric vehicle efficiency measured differently?
EVs typically use units like miles per kWh or kWh per 100 km, since they consume electricity rather than liquid fuel â an MPGe figure is sometimes used to roughly compare them against gasoline vehicles.
What does MPGe mean?
Miles per gallon equivalent â a figure that converts an electric vehicle's energy consumption into a gasoline-comparable number based on the energy content of a gallon of gasoline, for rough cross-comparison purposes.