Fill tank until it is completely full.
Set your trip odometer counter to zero or note the odometer reading.
The next time you fill up until the tank is completely full.
Make a note of how many litres needed to fill the tank.
Make a note of the odometer trip reading.
Enter these last two values into the calculator.
Enter your average km driven per day.
Application will return the consumption of fuel per 100 km and also the amount you spent in one month and over the year on your fuel.