Travel
Converting litres per 100 km to miles per gallon
Take the reciprocal, then apply two unit conversions. Litres per 100 km falls as efficiency rises, so mpg must be formed by dividing rather than multiplying.
The Formula
mpg = 100 / (L/100km) x 3.785411784 / 1.609344
Take the reciprocal, then apply two unit conversions. Litres per 100 km falls as efficiency rises, so mpg must be formed by dividing rather than multiplying.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| L/100km | Consumption in litres per 100 kilometres | litres per 100 km | Lower is better on this scale. |
| 3.785411784 / 1.609344 | Gallon and mile conversion | dimensionless | US litres per gallon divided by kilometres per mile; together about 2.352146. |
| mpg | Consumption in miles per US gallon | miles per US gallon | Higher is better on this scale — the opposite direction to litres per 100 km. |
What Each Symbol Means
L/100kmlitres per 100 km
Consumption in litres per 100 kilometres
Lower is better on this scale.
3.785411784 / 1.609344dimensionless
Gallon and mile conversion
US litres per gallon divided by kilometres per mile; together about 2.352146.
mpgmiles per US gallon
Consumption in miles per US gallon
Higher is better on this scale — the opposite direction to litres per 100 km.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate gas mileage page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Gas Mileage, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.