Quickly convert miles per gallon (MPG) to kilometers per liter (km/L). Supports both US and Imperial (UK) gallons. Includes the conversion formula, quick reference table, and tips to save fuel.
Efficiency Converter
How to Convert MPG to km/L
Converting Miles Per Gallon (MPG) to Kilometers per Liter (km/L) is a common requirement when importing vehicles or traveling between the US, UK, and metric-using countries. Because the US and the UK use different gallon sizes, the conversion factor depends on which system you are starting with.
The MPG to km/L Formula
To convert manually, use the following multipliers based on the standard definitions of miles, kilometers, and gallons:
- For US MPG: km/L = US MPG × 0.42514
- For UK (Imperial) MPG: km/L = UK MPG × 0.35401
MPG to km/L Quick Reference Table
This table compares common fuel economy ratings for both US and UK standards converted to the metric km/L equivalent:
| Miles Per Gallon (MPG) | Equivalent US km/L | Equivalent UK km/L |
|---|---|---|
| 15 MPG | 6.38 km/L | 5.31 km/L |
| 25 MPG | 10.63 km/L | 8.85 km/L |
| 35 MPG | 14.88 km/L | 12.39 km/L |
| 45 MPG | 19.13 km/L | 15.93 km/L |
| 60 MPG | 25.51 km/L | 21.24 km/L |
Context: Why do US and UK MPG differ?
A common point of confusion is that a car rated at "40 MPG" in a British car magazine seems much more efficient than the same car rated at "33 MPG" in the United States. This is due to the Gallon size:
- US Gallon: Approx. 3.785 Liters
- Imperial (UK) Gallon: Approx. 4.546 Liters (About 20% larger)
Because the UK gallon is larger, a vehicle can travel more miles on a single gallon of fuel in the UK system, even though its physical engine efficiency is identical to the US version.
Why Use Kilometers per Liter (km/L)?
While most of the world uses L/100km (which measures fuel consumption), many countries in Asia and Latin America prefer km/L (which measures fuel efficiency). It is often considered more intuitive because, like MPG, a higher number indicates a more efficient vehicle.