Convert MPG (US) to Kilometers per Liter
MPG (US) to kilometers per liter is the conversion you need when a car is rated in US miles per gallon but you measure fuel economy in metric distance per liter. One US mpg is approximately 0.425143707 km/L. Both units read the same way — distance per unit of fuel — so a higher mpg gives you a higher km/L, and the number simply gets smaller when you switch to the metric unit.
Miles per gallon (US) to Kilometers per liter conversion table
| Miles per gallon (US) (mpg (US)) | Kilometers per liter (km/L) |
|---|---|
| 1 | 0.425144 |
| 2 | 0.850287 |
| 3 | 1.275431 |
| 5 | 2.125719 |
| 10 | 4.251437 |
| 20 | 8.502874 |
| 50 | 21.257185 |
| 100 | 42.514371 |
| 500 | 212.571854 |
| 1,000 | 425.143707 |
The formula
To convert MPG (US) to kilometers per liter, multiply the US figure by 0.425143707:
km/L = mpg (US) × 0.425143707
A worked example
Say a car is rated at 30 mpg in US figures and you want kilometers per liter:
30 × 0.425143707 = 12.75 km/L
So 30 US mpg is about 12.75 km/L — the same efficiency, measured in metric distance and metric fuel.
Why it's an approximation
The factor 0.425143707 is a rounded value. It comes from two conversions stacked together: miles into kilometers on the distance side, and US gallons into liters on the fuel side. Neither of those divides evenly, so the combined factor is trimmed to a practical length. Add more decimal places if you need tighter precision.
When you'll use it
Comparing a US mpg rating against km/L figures on a metric spec sheet, or working out real fuel economy in countries that measure distance per liter. Unlike liters per 100 km, this one moves the same way as mpg — a higher km/L is the more efficient car.
Frequently asked questions
How many km/L is 30 US mpg?
About 12.75 km/L. Multiply 30 by 0.425143707 and you get 12.75. Both figures describe how far the car goes on a set amount of fuel, so a higher mpg always means a higher km/L.
Do mpg and km/L move in the same direction?
Yes. Both are distance per unit of fuel, so a more efficient car scores higher on both. That's different from liters per 100 km, which runs the opposite way. Here the km/L number just comes out smaller because a liter is smaller than a gallon.
Is the MPG (US) to km/L conversion exact?
No. The factor 0.425143707 is rounded, because converting miles to kilometers and US gallons to liters doesn't divide evenly. It's plenty accurate for comparing cars, but the digits continue past the cutoff.