Mondo Knows Tools
Fuel Economy Converter
MPG, L/100 km and km per litre, plus what a trip actually costs. Use the free fuel economy converter below to get an instant answer, with the formula shown so you can check the maths and trust the result. Free, private, and no sign-up.
Per gallon if you use miles, per litre if you use kilometres.
Mondo says
Litres per 100 km
7.8
L/100 km
US miles per gallon30
Imperial miles per gallon36
Kilometres per litre12.75
Litres per 100 km7.8
Kilometres per imperial gallon
a UK gallon is bigger58
a UK gallon is bigger58
Fuel for 300 miles37.9 L (10 US gal)
Trip cost$34.50
Cost each way unit$0.12 per mile
A lower L/100 km figure is better, while a higher MPG figure is better, so the two move in opposite directions. Check tyre pressure before blaming the car.
How it works
Miles per gallon goes up when a car gets better; litres per 100 kilometres goes down. That inversion is why comparisons between the two feel wrong, so this page shows all four units at once, then turns your own fuel price and trip length into a running cost.
The formula
L/100 km = 235.215 ÷ US MPG. US MPG = 0.425 × UK MPG. Trip cost = distance ÷ economy × price per unit.Fuel Economy Converter: common questions
- What does the Fuel Economy Converter work out?
- MPG, L/100 km and km per litre, plus what a trip actually costs. It is one of the Unit Converters tools on Mondo Knows.
- How is the Fuel Economy Converter calculated?
- Miles per gallon goes up when a car gets better; litres per 100 kilometres goes down. That inversion is why comparisons between the two feel wrong, so this page shows all four units at once, then turns your own fuel price and trip length into a running cost. The maths is short enough to check by hand: L/100 km = 235.215 ÷ US MPG. US MPG = 0.425 × UK MPG. Trip cost = distance ÷ economy × price per unit.
- Do I need to sign up, and is my data stored?
- No sign-up, and nothing you type is sent anywhere. The calculation runs in your own browser, so the figures stay on your device and the page works offline once loaded.
Mondo also knows
Fuel Cost CalculatorWhat a trip costs in fuel.🧭 Everyday & TechSpeed ConverterConvert mph, km/h, m/s, knots and feet per second.📐 Unit ConvertersVolume ConverterConvert litres, gallons, cups, pints and millilitres.📐 Unit ConvertersLength ConverterConvert metres, feet, miles, inches and more at once.📐 Unit Converters
Estimates for general guidance only. This is not financial, medical or legal advice. Everything runs in your browser and nothing you type is stored.