Fuel efficiency converter
Convert fuel economy between km/L, L/100km, US mpg and UK mpg using reciprocals. Example: 8 L/100km is 12.5 km/L, 29.401823 US mpg, 35.310132 UK mpg.
What to know
The fuel-efficiency page converts four ways of stating consumption: kilometres per litre, litres per 100 km, miles per US gallon and miles per UK gallon. Conversions run through km/L, using 1 US mpg = 0.425143707 km/L and 1 UK mpg = 0.35400604 km/L.
L/100km is the reciprocal of km/L scaled by 100, so the direction flips: a bigger L/100km figure is a thirstier car. Worked example: 8 L/100km is 100 / 8 = 12.5 km/L, which divided by 0.425143707 gives 29.401823 US mpg and divided by 0.35400604 gives 35.310132 UK mpg.
The US and UK gallons differ by about 20 percent, which is why the same car quotes 29.4 mpg in a US brochure and 35.3 mpg in a UK one. Check which gallon your source uses before comparing numbers.
Because of the reciprocal formulas, the value must be greater than zero, and a zero input is rejected. The default pair is km/L to L/100km, so 12.5 gives 8.
Rules of thumb: 5 L/100km is 20 km/L, 10 L/100km is 10 km/L and 15 L/100km is 6.666667 km/L. Because the scale is reciprocal, halving consumption doubles the distance per litre, so going from 10 to 5 L/100km takes you from 10 to 20 km/L.
Choose a specific task 12
Related tools 1
How to use Fuel efficiency converter
- Type 8 in the Value field.
- Select L/100km in From and km/L in To.
- Read the Result line, which shows 12.5 km/L.
- Change To to mpg (US) for 29.401823, or to mpg (UK) for 35.310132.
Quick answers
What is 35 mpg (US) in L/100km?
About 6.720417 L/100km, from 100 / (35 x 0.425143707).
Why can a smaller number be better in one unit and worse in another?
Because L/100km measures fuel used per distance while mpg and km/L measure distance per fuel. They are reciprocals, so they move in opposite directions.
Can I enter 0?
No. A zero value would require dividing by zero, so the page asks for a number above 0.