Converters
Fuel Economy Converter
Convert US or UK mpg and L/100 km.
Free to use — no sign-up or login.
Converted
Amortization schedule
| # | Date | Payment | Principal | Extra | Interest | Balance |
|---|---|---|---|---|---|---|
US mpg divides 235.214583 by the mpg figure. UK mpg divides 282.480936, because an imperial gallon is larger. Thirty US mpg is 7.84 L/100 km. Thirty UK mpg is 9.42 L/100 km.
The gallon sizes in liters are on the volume converter. A lower L/100 km is better. A higher mpg is better.
The two gallons
The US factor comes from 1 mile = 1.609344 km and 1 US gallon = 3.785411784 L. The UK factor uses 1 imperial gallon = 4.54609 L. The same car therefore has two mpg numbers.
Direction
mpg to L/100 km divides the factor by your mpg. L/100 km to mpg divides the same factor by the liters figure. The result is shown to two decimals.
Worked example: 30 mpg
US gallons, mpg to L/100 km, value 30: 7.84 L/100 km. UK gallons with the same 30 mpg: 9.42 L/100 km. Those are not the same car.
\[ 30\,\mathrm{mpg_{US}}=7.84\,\mathrm{L/100\,km} \]
Frequently asked questions
What is 30 US mpg in L/100 km?
7.84.
What is 30 UK mpg in L/100 km?
9.42. The imperial gallon is larger, so the same mpg number means more fuel.
Which number is better?
For L/100 km, lower is better. For mpg, higher is better.
Why is the UK factor bigger?
An imperial gallon is 4.54609 L and a US gallon is 3.785411784 L.
Does this estimate a trip cost?
No. It converts a fuel-economy figure. It does not use distance, price, or tank size.
References
Assumptions and limitations
Not a trip-cost or tank-fill calculator. US and UK gallons must be chosen. Results show two decimal places.