YOUR FUEL ECONOMY, MEASURED
Fuel Economy Calculator
Enter the distance you drove and the fuel you used to calculate your actual MPG, litres per 100 km and kilometres per litre.
Your distance.
Your fuel used.
Your fuel economy.
THE FULL-TANK METHOD
How to measure your fuel economy
- Fill your tank and reset the trip meter, or record the odometer reading.
- Drive normally, then refill to the same level. Stopping at the pump's first automatic shutoff both times helps make the fills comparable.
- Enter the distance driven since the first fill and the fuel added at the second fill. The refill amount estimates the fuel used over that distance.
L/100 km = (litres used ÷ kilometres driven) × 100
MPG = miles driven ÷ gallons used
For example, 40 L over 500 km gives 8 L/100 km, about 29.4 U.S. MPG or 35.31 Imperial MPG.
A U.S. gallon is about 3.785 L and an imperial gallon is about 4.546 L. The same drive therefore yields a higher Imperial MPG. See NIST's unit conversion factors.
Read the MPG and L/100 km measurement guide or use your result to estimate trip fuel cost.
Calculate your fuel economy from distance and fuel used
Enter the distance you drove and the fuel you used over that same distance. To calculate gas mileage in U.S. MPG, choose miles and U.S. gallons. You can also enter mixed units, such as miles and litres, without converting either measurement first. The results show U.S. MPG, imperial MPG, L/100 km and km/L for the same drive.
If you are using a pump receipt, start from a full tank and use the amount needed to refill it after driving. The refill measures fuel used over the distance since the last full tank. Tank capacity and the amount paid do not measure that fuel use.
Fuel economy formulas
| Result | Calculation | What improves |
|---|---|---|
| U.S. MPG | Miles ÷ U.S. gallons used | Higher is better |
| Imperial MPG | Miles ÷ imperial gallons used | Higher is better |
| L/100 km | Litres used ÷ kilometres × 100 | Lower is better |
| km/L | Kilometres ÷ litres used | Higher is better |
One mile is 1.609344 km. A U.S. gallon holds about 3.78541 L and an imperial gallon holds 4.54609 L. The larger imperial gallon gives a higher MPG number for the same fuel use. Compare figures in the same unit. The NIST Guide to the SI lists the conversion factors.
Two worked fuel economy examples
You drove 410 miles and refilled with 13 U.S. gallons. Divide 410 by 13 to get 31.54 U.S. MPG. The same drive is 37.88 imperial MPG, 7.46 L/100 km or 13.41 km/L.
On a different drive, you covered 610 km and used 46 L. Divide 46 by 610 and multiply by 100 to get 7.54 L/100 km. That drive is equivalent to 31.19 U.S. MPG, 37.46 imperial MPG or 13.26 km/L.
Average fuel economy over several fills
Add up all the distances and all the fuel used, then run the calculator on those totals. An average of individual MPG or L/100 km figures can be misleading because the trips may cover different distances or use different amounts of fuel.
For example, 250 km on 20 L followed by 350 km on 25 L is 600 km on 45 L, or 7.50 L/100 km. If you make a partial fill, include it in the fuel total from the starting full tank through the next full tank. Match that total to the distance driven over the same period.
Compare your result with a vehicle rating
Your result reflects your own driving and conditions. A published combined rating uses a standardized mix of city and highway driving. Check Natural Resources Canada’s fuel consumption guide for the meaning of the ratings and make sure the gallon type matches before comparing MPG figures.
For a step-by-step measurement and conversion walkthrough, read how to calculate MPG and L/100 km. To find out what a difference in fuel economy means in dollars, enter both vehicle ratings in the Hybrid vs Gas Cost Calculator.