mpg (US) to km/L Converter
Convert mpg (US) to km/L instantly with a reference conversion table.
| mpg (US) | km/L |
|---|
How to convert mpg (US) to km/L
Enter your value
Type the number of mpg (us) you want to convert into the left box. The result in km/l appears instantly in the right box. You can also type into the right box to convert in the other direction.
Use the swap button
Click the ⇄ Swap button to reverse the conversion — km/L to mpg (US). Your current value carries across so you don't have to re-enter anything.
About mpg (US) and km/L
Mpg (US) measures distance per gallon, while km/L measures distance per liter — both express fuel efficiency as "distance traveled per unit of fuel," just using different units for distance and volume. Since a US gallon is about 3.785 liters, converting between the two systems means accounting for both the distance-unit change (miles to km) and the volume-unit change (gallons to liters) at once, which is why the conversion factor (0.425144) isn't a simple round number.
Comparing fuel economy across countries
US vs UK gallons matter too
A US gallon (3.785L) and a UK imperial gallon (4.546L) are different sizes, so an mpg figure quoted in the UK isn't directly comparable to a US mpg figure for the same car, even before converting to km/L. Always check which gallon definition a source is using — car reviews, spec sheets, and forums from different countries can mix the two without saying so.
Why L/100km reads "backwards" from mpg
Higher mpg or km/L numbers mean better efficiency, but lower L/100km numbers mean better efficiency — the scale runs in the opposite direction because it measures fuel consumed per fixed distance rather than distance covered per unit of fuel. This trips up a lot of people comparing a US car's mpg sticker against a European car's L/100km spec sheet.
Test-cycle ratings vs real-world driving
Official fuel economy figures (EPA in the US, WLTP in Europe and much of Asia) are measured under standardized lab conditions that don't perfectly match everyday driving — real-world mpg or km/L is often somewhat lower, especially in stop-start city traffic, cold weather, or with a heavily loaded vehicle. Converting between units doesn't change this gap; it's worth keeping in mind when comparing a manufacturer's advertised figure to your own fill-up calculations.
1 US MPG = 0.4251 km/L. A 25 US MPG car achieves 10.63 km/L. Japanese and European fuel efficiency ratings use km/L or L/100km rather than mpg, so a car's US window-sticker rating needs converting before it can be compared against a Japanese or European spec sheet. A 'good' 30 US MPG works out to about 12.75 km/L, or roughly 7.8 L/100km.
| mpg (US) | km/L |
|---|---|
| 5 | 2.126 |
| 10 | 4.251 |
| 15 | 6.377 |
| 20 | 8.503 |
| 25 | 10.63 |
| 30 | 12.75 |
Frequently asked questions
How do I convert mpg (US) to km/L?
To convert mpg (US) to km/L, multiply by 0.425144. Or use the calculator above for instant results.
How many km/L are in 1 mpg (US)?
1 mpg (US) equals 0.425144 km/L.
Is the mpg (US) to km/L converter free?
Yes, the mpg (US) to km/L converter is completely free with no sign-up required, no downloads, and it works offline once the page has loaded.
Why is a US gallon different from a UK gallon in mpg figures?
A US gallon is about 3.785 liters, while a UK imperial gallon is about 4.546 liters — roughly 20% larger. This converter uses the US gallon definition, so UK-sourced mpg figures need their own separate conversion first.
Why do other countries use km/L or L/100km instead of mpg?
Most of the world uses the metric system, so fuel efficiency is expressed in km/L or L/100km. L/100km is popular in Europe because it scales linearly with fuel cost — a car using 10 L/100km uses exactly twice the fuel of one using 5 L/100km.
How do I convert km/L to L/100km?
Divide 100 by the km/L figure. A car achieving 12.75 km/L works out to 100 ÷ 12.75 ≈ 7.84 L/100km. A "better" efficiency car has a higher km/L number but a lower L/100km number.
What counts as good fuel economy in km/L?
A typical modern gasoline sedan achieves 12-17 km/L (28-40 US mpg), hybrids often reach 20-25+ km/L (47-59+ US mpg), and large SUVs commonly sit around 6-10 km/L (14-24 US mpg).