Gas is a major expense in many households. Calculating exactly how many miles per gallon your car actually gets on a trip can be valuable information. It can help you predict future gasoline costs and help you plan out your overall budget.
Fill up your gas tank. Filling up the tank will provide the most accurate results. You do not need to record the gallons used for this initial fill up.
Reset the trip odometer to zero. If you car does not have a trip odometer, write down the exact mileage on your odometer instead. Odometers are usually located under the speedometer.
Keep track of the gas bought. Record the gallons of gas you bought on your trip. Do not round the gallons to the nearest whole number.
Calculate the total number of gallons needed. At the end of your trip, refill your tank again until it is full and record the number of gallons used. Add this to the gallons purchased throughout your trip, but do not include the initial fill up.
Calculate the total number of miles driven. At the end of your trip, record the number of miles recorded on the trip odometer. If you used the regular odometer, write down that number. Subtract the initial reading in Step 2 from this higher number. This new number will be the number of miles driven on your trip.
Calculate your gas mileage. Divide the total number of miles from Step 4 by the total number of gallons purchased on your trip from Step 5. The answer will be the number of miles per gallon your car got during your trip. Example: 212.45 miles divided by 10.26 gallons equals 20.7 miles per gallon
