Travel
Litres per 100 km and miles per gallon are reciprocals
One constant converts either way, because the two units are reciprocal. The constant applies to US gallons.
The Formula
mpg = 235.214583 / (L/100km)
One constant converts either way, because the two units are reciprocal. The constant applies to US gallons.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| 235.214583 | Conversion constant | dimensionless | Equals 100 km ÷ 1.609344 km/mi × 3.785411784 L/gal. |
| L/100km | Consumption in litres per 100 kilometres | litres per 100 km | Lower is better on this scale. |
| mpg | Consumption in miles per gallon | miles per US gallon | Higher is better on this scale — the opposite direction. |
What Each Symbol Means
235.214583dimensionless
Conversion constant
Equals 100 km ÷ 1.609344 km/mi × 3.785411784 L/gal.
L/100kmlitres per 100 km
Consumption in litres per 100 kilometres
Lower is better on this scale.
mpgmiles per US gallon
Consumption in miles per gallon
Higher is better on this scale — the opposite direction.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate fuel cost 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 Fuel Cost, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.