Conversion table
| US mpg | L/100km | km/L |
|---|---|---|
| 10 | 23.52 | 4.25 |
| 15 | 15.68 | 6.38 |
| 20 | 11.76 | 8.5 |
| 25 | 9.41 | 10.63 |
| 30 | 7.84 | 12.75 |
| 35 | 6.72 | 14.88 |
| 40 | 5.88 | 17.01 |
| 45 | 5.23 | 19.13 |
| 50 | 4.7 | 21.26 |
| 60 | 3.92 | 25.51 |
US vs UK gallons
A US gallon is 3.785 L; an imperial (UK) gallon is 4.546 L. For UK mpg use L/100km = 282.481 ÷ mpg — the same car shows a higher mpg figure in the UK.
Why the formula is “upside down”
mpg measures distance per fuel; L/100km measures fuel per distance. That is why converting means dividing a constant by the value, and why going from 10 to 20 mpg saves far more fuel than going from 40 to 50 mpg.
Frequently asked questions
What is 30 mpg in L/100km?
7.84 L/100km.
What is 40 mpg in L/100km?
5.88 L/100km.