Three ways to measure economy
Fuel economy can be written as litres per 100 km (lower is better), kilometres per litre (higher is better) or miles per gallon (higher is better). They describe the same thing from different angles. This tool takes the distance and fuel you actually used and reports all three, so you can compare a car against any figure you're quoted.
Real-world vs. official figures
Manufacturer economy figures come from standardized lab tests and are often better than what you'll see day to day. Measuring your own economy — fill up, drive, fill up again and note the litres — gives a real number for your driving, roads and load.
Save fuel with small changes
Steady speeds, correct tyre pressure, less idling and lighter loads all improve economy. Tracking it over a few tanks shows whether a change actually helps.
Frequently asked questions
US or UK gallons?
This tool uses US gallons for the MPG figure. A UK (imperial) gallon is larger, so imperial MPG numbers look higher for the same economy.
How do I measure it accurately?
Fill the tank, reset the trip meter, drive normally, then refill and note the litres. Distance divided into fuel gives your real economy.
How do I calculate fuel economy?
Divide the distance travelled by the fuel used. In metric it is usually shown as litres per 100 km; in the US as miles per gallon.
How do I convert between L/100km and MPG?
They are inverse measures, so you divide 235.2 by one to get the other. 8 L/100km is about 29 MPG.
How do I estimate the fuel cost of a trip?
Multiply the distance by your consumption and by the fuel price. The tool combines them into a total for the journey.