Liters per 100 km to Miles per Gallon (US) Converter

This page converts to US mpg, based on the US gallon. A UK gallon is larger, so the same car scores a higher mpg figure in UK terms. If you are comparing against a British review or brochure, change the To menu to Miles per Gallon (UK):

Comparing a US figure with a UK one without noticing which is which makes the UK car look about 20% more economical than it is.

Litres per 100 km measures fuel used over a fixed distance; mpg measures distance covered on a fixed amount of fuel. One is the upside-down of the other, so the converter divides instead of multiplying: mpg = 235.215 ÷ L/100km. A lower L/100km figure means better economy and a higher mpg.

Because of the division, equal steps in L/100km are not equal steps in mpg. Going from 4 to 5 L/100km drops 58.8036 to 47.0429 mpg, a fall of about 11.8. Going from 10 to 11 L/100km drops 23.5215 to 21.3831 mpg, a fall of only about 2.1. The litre of extra fuel per 100 km is the same in both cases.

In your head, divide 235 by the L/100km value. That is only 0.09% low: 235 ÷ 8 = 29.375 against the converter's 29.4018. Using 240 makes the division easier for some numbers but runs 2% high, giving exactly 30 mpg for 8 L/100km. For UK mpg, the constant is 282.481, so divide about 282 by the figure instead.

When you want to know what a trip costs, L/100km is the more direct number, because fuel used scales in a straight line with it. A 500 km drive at 8 L/100km uses 40 litres; at 6 L/100km it uses 30. Convert to mpg for discussion, but do fuel and cost sums in L/100km.

Entering 0 or a negative number gives no result: zero fuel per 100 km would mean infinite mpg, and negative fuel use has no meaning.