Fuel Economy Calculator & Converter
Fuel economy converter
Trip fuel cost
MPG (US) and MPG (UK) differ because the US and Imperial gallons aren’t the same size. Costs are computed in whatever currency you type the fuel price in — nothing is converted between currencies.
Fuel calculator FAQ
How do I convert MPG to L/100km?
Enter your MPG above and pick the unit — we instantly show the L/100km, km/L and the other MPG equivalent. The math: L/100km = 235.215 ÷ MPG (US).
Why are US MPG and UK MPG different?
Because the gallons aren’t the same size: a US gallon is 3.785 L while an Imperial (UK) gallon is 4.546 L. So the same car shows a higher number in UK MPG than US MPG.
How is the trip fuel cost calculated?
We work out the litres your trip needs (distance ÷ fuel economy), then multiply by your fuel price. Enter the price in your own currency — the result comes back in that same currency, so it works anywhere.
Which unit should I use?
Use whatever your country uses: MPG in the US/UK, L/100km across most of Europe, and km/L in places like Brazil and Japan. The converter shows all of them at once.