How to calculate fuel consumption

Miles per gallon and litres per 100 km calculators:

To calculate your vehicles actual fuel consumption you need to know two numbers: the distance travelled and the amount of fuel used to travel that distance.
Here is one easy way to calculate fuel consumption:
- Fill up your tank to the first click-off and reset the trip odometer to zero.
- Drive.
- Next time you come to a gas station for a fill-up, write down your trip odometer readings, fill the tank the same way, to the first click-off and write down the amount of fuel it took. Now you've got what you need: the amount of fuel used and the distance travelled between fill-ups.

Miles Per Gallon

To calculate your MPG, divide the total number of miles driven between fill-ups by the number of gallons used:

MPG = miles driven / gallons used.

For example: You filled up your tank and zeroed the trip odometer. Next time you at the gas station, your trip odometer shows 320 miles and it took 18.5 gallons to fill up the tank again. That means your car consumed 18.5 gallons to drive 320 miles. So the calculation is:

320 miles / 18.5 gallons = 17.3 MPG

Litres per 100 kilometres

For a Metric System, you need to multiply the number of litres consumed by 100 and then divide by the kilometres driven. The formula is:

L/100 km = number of Litres x 100 / number of kilometres.

For example: You filled up your tank and zeroed the trip odometer. Next time you at the gas station, your trip odometer shows 480km and it took 42 Litres to fill up the tank again. That means your car consumed 42 litres to drive 470 kilometres, or its fuel economy is:

42L x 100 / 470 = 8.9 L/100 km