Why is converting mpg to L/100km not a simple multiply?

Because they measure opposite things. Miles per gallon is distance per fuel, so higher is better, while litres per 100 km is fuel per distance, so lower is better. Converting one to the other means dividing into a constant rather than multiplying, which is why the relationship is inverse, not linear.

Is US mpg the same as UK mpg?

No. They use different gallons: the US gallon is smaller, so the same car shows a lower number in US mpg than in UK mpg. A car rated 40 mpg in the UK is only about 33 mpg in US terms. The converter handles both so you can compare like with like.

How accurate are the conversions?

Each conversion uses the exact, internationally defined factor for the unit, not a rounded approximation, so the maths is precise. The result is shown to several significant figures and rounded only for display. For everyday and most professional use, the figures are exact to well beyond the precision you need.

Does this work offline and is anything sent to a server?

The conversion runs entirely in your browser, so nothing you type is sent anywhere, and once the page has loaded it keeps working with no connection. There is no sign-up and no limit on how many conversions you make.

Fuel Economy Converter

Convert fuel economy between miles per gallon (US and UK), litres per 100 km and kilometres per litre. Type a value and compare a car across every measure. A free, exact fuel economy converter that runs in your browser.

Exact, standard factors
100% free
No sign-up, no app
Instant as you type
Works offline after first load

Read the guide: How to Convert MPG to L/100km

Convert

From

235.21458L/100km

1 mpg = 235.21458 L/100km

1 mpg in every unit

Litres per 100 km235.21458 L/100km

Kilometres per litre0.42514371 km/L

Miles per gallon (US)1 mpg

Miles per gallon (UK)1.2009499 mpg

How to use it

1
Enter a value

Type the number you want to convert. The result updates as you type, with no button to press.
2
Pick the units

Choose what you are converting from and to. Swap them with one click if you need the reverse.
3
Read or copy

See the exact result, plus a table of your value in every unit. Copy any line you need.

When it comes in handy

Comparing cars

Put a US mpg figure and a European L/100km figure on the same footing before you compare two cars.

Driving abroad

Make sense of a hire car or fuel sticker that uses the units you are not used to.

Tracking your own use

Convert your measured economy into whichever unit your records or apps expect.

Instant, exact & 100% in your browser

The conversion runs right here in your browser using exact, standard factors. Nothing you type is sent to a server, there is no sign-up and no limit, and once the page has loaded it keeps working even with no connection.

Frequently asked questions

Why is converting mpg to L/100km not a simple multiply?: Because they measure opposite things. Miles per gallon is distance per fuel, so higher is better, while litres per 100 km is fuel per distance, so lower is better. Converting one to the other means dividing into a constant rather than multiplying, which is why the relationship is inverse, not linear.
Is US mpg the same as UK mpg?: No. They use different gallons: the US gallon is smaller, so the same car shows a lower number in US mpg than in UK mpg. A car rated 40 mpg in the UK is only about 33 mpg in US terms. The converter handles both so you can compare like with like.
How accurate are the conversions?: Each conversion uses the exact, internationally defined factor for the unit, not a rounded approximation, so the maths is precise. The result is shown to several significant figures and rounded only for display. For everyday and most professional use, the figures are exact to well beyond the precision you need.
Does this work offline and is anything sent to a server?: The conversion runs entirely in your browser, so nothing you type is sent anywhere, and once the page has loaded it keeps working with no connection. There is no sign-up and no limit on how many conversions you make.