The trip
From a fill-up: distance driven and fuel used.
Consumption
How this fuel calculator works
Use it in two ways: from a fill-up (distance driven and fuel used) to get consumption, or from a known consumption to see how much fuel a trip needs.
In Europe, Russia and Brazil people usually quote litres per 100 km: a smaller number means the car is more economical. Kilometres per litre is the inverse — bigger is better. Miles per gallon here uses the US gallon (3.785 L), not the British imperial gallon.
Price per litre or gallon is optional. If you enter it, we show the trip cost. This is tank arithmetic, not a WLTP or EPA lab cycle.
L/100 km, km/L and mpg
L/100 km = litres ÷ km × 100. km/L = km ÷ litres. US mpg = miles ÷ US gallons.
Example: 100 km on 6.5 L → 6.50 L/100 km, 15.38 km/L, 36.19 mpg. The same car needs 13.00 L for 200 km.
mpg = miles ÷ gallons
How to calculate fuel consumption
- Choose a mode: From a trip if you have distance and fuel used. Fuel needed if you already know L/100 km or mpg.
- Pick units and enter the figures: Metric (km, litres) or US (miles, gallons). Price is optional.
- Read all three ratings: L/100 km, km/L and mpg update together, plus cost if you typed a price.
Frequently asked questions
Is a lower L/100 km better?
Yes. 5 L/100 km uses less fuel than 8. For mpg and km/L, higher is better.
US or imperial gallon?
US gallon (3.785 L). The UK imperial gallon is larger (4.546 L); this page does not use it.
Will this match the sticker on the car?
Stickers are lab cycles (WLTP, EPA). Real roads, load and air-con differ. Use a fill-up for your own figure.
Can I mix km and gallons?
No. Switch the unit tab so distance and fuel match. We then convert internally to show all three ratings.