Fuel Economy Converter
Convert between Fuel Economy units. Choose from 5 different units including Kilometers per Liter, Liters per 100km, Miles per Gallon (US).
Popular Conversions
All Units
| From | Kilometers per Liter (km/L) |
|---|---|
| Kilometers per Liter (km/L) | — |
| Liters per 100km (L/100km) | — |
| Miles per Gallon (US) (mpg) | — |
| Miles per Gallon (UK) (mpg (UK)) | — |
| Miles per Liter (mi/L) | — |
How efficiency gets measured
Fuel economy describes how far a vehicle travels for a given quantity of fuel — or, flipped around, how much fuel it burns to cover a given distance. That inversion is the whole drama of the category. km/L, MPG-US, and MPG-UK all reward higher numbers, while Europe's L/100 km rewards lower numbers because it counts consumption rather than range.
Two gallons, two stories
The split between US and Imperial gallons dates to 1824, when Britain redefined its gallon as 4.546 L while the United States kept the older Queen Anne wine gallon of 3.785 L. The result: an MPG-UK figure looks roughly 20 percent more flattering than the MPG-US figure for the exact same car. UK motoring press and manufacturer brochures still routinely quote mpg(UK), which is why a Honda or Volkswagen reviewed in London and in California can appear to be two different cars.
What the dashboard shows now
Regional habits are sticky. Continental Europe and Japan publish L/100 km on window stickers, while the US, the UK, and much of the Commonwealth still default to MPG. Fleet operators increasingly track L/100 km regardless of country because it scales linearly with fuel cost. Electric vehicles complicate the picture by reporting km/kWh or mi/kWh — conceptually fuel economy, but measuring energy rather than liquid.
The non-linearity nobody warns about
The biggest pitfall is treating MPG improvements as linear. Going from 10 to 20 mpg saves far more fuel over a fixed distance than going from 30 to 60 mpg, even though both "double" the figure. L/100 km exposes this honestly: 23.5 → 11.8 is a much bigger drop than 7.8 → 3.9. A few other classic slips:
- Comparing US and UK MPG numbers without converting — a 20 percent phantom gap.
- Assuming highway and combined-cycle figures are interchangeable.
- Mixing km/L and L/100 km without remembering the inverse relationship.