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MPG to L/100km Converter

Converts fuel economy between US mpg, UK mpg, L/100 km, and km/L from any field, and works out the fuel cost of a trip from the fuel price you enter.

Country
US mpg
The usual unit in United States
UK mpg
L/100 km
km/L

Type a number in any field to see the other three units.

For mpg and km/L, higher is better. For L/100 km, lower is better.

The UK gallon (4.546 L) is larger than the US gallon (3.785 L), so the UK mpg figure is higher for the same car.

Fuel economy conversion chart

Fuel economy conversion chart
L/100 kmUS mpgUK mpgkm/L
458.870.625
54756.520
639.247.116.7
733.640.414.3
829.435.312.5
1023.528.210
1219.623.58.33

Trip fuel cost

Distance unit
mi
Currency
Price is per
USD
Enter today's price at your station.

Enter a fuel economy above, then a distance and a fuel price.

This tool changes only the unit. It does not convert between test standards such as EPA and WLTP.

The cost is an estimate based on the numbers you enter.

Official ratings and real-world fuel economy can differ.

How to use the fuel economy converter

  1. Check the country. The unit that country uses moves to the top.
  2. Type the fuel economy you know in its field. For mpg, pick the US or the UK field.
  3. Read the other three units in the fields and in the result line.
  4. Copy the result line if you need it.
  5. For trip cost, enter the distance and the fuel price at your station.

What is fuel economy conversion?

Fuel economy conversion changes the fuel use of a car from one unit to another, such as miles per gallon (mpg) to liters per 100 kilometers (L/100 km). Countries report the same measurement in different units: the United States uses US mpg, the United Kingdom uses UK mpg, most of Europe, Canada, and Australia use L/100 km, and Japan and South Korea use km/L.

The units run in opposite directions. Mpg and km/L give the distance per amount of fuel, so a higher number is better. L/100 km gives the fuel per distance, so a lower number is better.

How the units are converted

  • One US gallon is 3.785411784 L, one imperial (UK) gallon is 4.54609 L, and one mile is 1.609344 km. These are defined values.
  • L/100 km is 235.215 divided by US mpg, or 282.481 divided by UK mpg.
  • Km/L is 100 divided by L/100 km. One US mpg is about 0.4251 km/L, and one UK mpg is about 0.3540 km/L.
  • The imperial gallon is about 20% larger than the US gallon, so the UK mpg of a car is about 1.201 times its US mpg.
  • Trip fuel is the distance divided by the fuel economy, and trip cost is that fuel multiplied by the price per unit of fuel.

When to use it

  • Reading a European or Japanese car review in L/100 km or km/L when you think in mpg.
  • Comparing a US review with a UK review of the same car.
  • Comparing rental cars before a trip to a country that uses another unit.
  • Estimating the fuel cost of a road trip and splitting it between passengers.

Questions about fuel economy units

How do I convert mpg to L/100 km?

Divide 235.215 by the US mpg figure, or divide 282.481 by the UK mpg figure. For example, 30 US mpg is 7.84 L/100 km, and 30 UK mpg is 9.42 L/100 km.

Why is UK mpg higher than US mpg for the same car?

The two countries use different gallons. An imperial gallon is 4.546 L and a US gallon is 3.785 L. A car goes farther on the larger gallon, so its UK mpg is about 20% higher. A car rated 40 US mpg is rated about 48 UK mpg.

Does this convert between EPA and WLTP ratings?

No. This tool changes only the unit. EPA, WLTP, and the Japanese and Korean test cycles measure cars in different ways, so the ratings of the same car differ even in the same unit. Real-world fuel economy also differs from every official rating.

Where does the fuel price come from?

You enter it. The tool does not fetch fuel prices. Type the price you see at your station, and choose whether it is per liter, per US gallon, or per UK gallon. The cost is an estimate based on the numbers you enter.

Does the currency setting convert money?

No. The currency only sets the symbol in front of the cost. The tool does not use exchange rates. Enter the fuel price in the same currency you want for the result.

How are the results rounded?

The calculation uses the full defined values. Only the displayed numbers are rounded: two decimal places below 10, and one decimal place from 10 upward. Your inputs and choices stay in your browser and are not sent to a server.