How to Calculate Gas Mileage

The formula to calculate gas mileage is really very simple.

Just follow these easy steps to calculate your MPG and track your increased fuel efficiency.

  1. Drive your car until you reach 1/4 of a tank of gas.
  2. Note the miles on your odometer at the gas station.
  3. Fill the tank completely.
  4. Write down the odometer reading on your receipt.
  5. Write the gallons of gas you pumped if not already printed on your receipt.
  6. Repeat all the above steps the next time you fill up the gas tank.
  7. Subtract your odometer readings to calculate Miles Driven

    Odometer Reading #2 - Odometer Reading #1 = Miles Driven

  8. Calculate gas mileage.

    Miles Driven/Gallons of Gas Pumped 2nd Time = MPG (Miles Per Gallon)


Say that you fill up my tank with 20 gallons of gas. The odometer reading is at 30,000 miles.

The next time you fill up my tank, you fill it with about 19 gallons of gas. The odometer reading is at 30,500.

30,500 - 30,000 = Miles Driven = 500

500/19= 26.32 MPG (approx.)

After you've calculated your gas mileage the first time, you should continue these steps every time you gas up. The only difference is that you should try many of my better gas mileage tips to improve gas mileage in your car.

Keep a spreadsheet of your calculations. Keep track of the different tips you've used from this web site. Note how those changes have affected your MPG.

Save your spreadsheets. You may be surprised - and delighted - by how much you save on gas if you implement our driving tips and techniques, and especially if you modify your vehicle or otherwise use new technology to increase your fuel efficiency.

Say that you decided to implement a few of the driving tips for better gas mileage laid out on this web site.

You go and gas up again at 32,000 miles. You put in about 19 gallons of gas again.

Your previous odometer reading was 30,500. So you do the subtraction to calculate miles driven.

31,200 - 30,500 = 700 miles driven

700/19 gallons of gas = 36.82 MPG

A noticeable improvement!

If you make the effort, and are persistent in your efforts to record your vehicle's gas mileage, you'll be on the road to significant fuel savings. Calculate your gas mileage every time you visit the pump and keep track of your progress as you become a more fuel efficient driver.

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