Gas Mileage Calculator – Estimate Fuel Economy

Enter the distance driven in miles and the gasoline consumed in gallons to find the fuel economy in miles per gallon. You can also enter your odometer readings to calculate the distance traveled.

Calculate Using Distance Traveled

Optionally enter the price per gallon or liter

Calculate Using Current and Previous Odometer Readings

Optionally enter the price per gallon or liter

Gas Mileage:

Cost per Mile
Learn how we calculated this below

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Do you want to calculate fuel consumption in liters per 100 kilometers or kilometers per liter?

How to Calculate Gas Mileage

Gas mileage, also known as fuel economy, is usually measured in miles per gallon, or MPG, in the US. It is a measure of how efficiently a vehicle uses fuel.

The better your fuel economy (the higher its MPG), the farther you can go on a gallon of gasoline, reducing your cost of traveling any given distance.

Fuel economy is affected by a number of factors, including:

  • The size and weight of your vehicle
  • The power output of its engine
  • Its aerodynamics, or how smoothly it slips through the air
  • The type of driving you do (city vs. highway)
  • Your driving style (aggressive vs. gentle)
  • The speed you drive (at the speed limit vs. over it)

While you cannot affect things like the size, weight, power, and aerodynamics of your vehicle (until you buy your next one, anyway), you can control your driving style and your speed. Gentle driving within the speed limit will definitely improve your fuel economy.

Our gas mileage calculator will let you easily determine your MPG, as well as any improvements you make to it through changes in your driving style.

Gas Mileage Formula

You can use a simple formula to calculate gas mileage. Divide the distance driven (in miles) by the fuel used (in gallons) to find the fuel economy (in MPG).

MPG = distance [miles] ÷ fuel used [gallons]

For example, let’s find the fuel economy (in MPG) of a vehicle that drives 100 miles and uses 6 gallons of gasoline to get there.

fuel economy = 100 ÷ 6
fuel economy = 16.67 MPG

Try our fuel economy conversion calculators to convert MPG to L/100km or km/L.

Steps to Calculate Gas Mileage

To use this formula, you will need to know the distance driven (in miles) and the amount of fuel consumed (in gallons).

Start by completely filling up the tank in your vehicle. Make sure to record the vehicle’s odometer reading before you leave the gas station (or reset your trip odometer to zero).

Then, drive as you normally would until you stop to refuel.

At the gas station, record the new odometer reading (or check the number of miles you traveled on the trip odometer). Then, fill up your tank again and record the number of gallons it took to do this.

Determine the distance driven by subtracting the previous odometer reading from the current odometer reading (or refer to the reading on the trip odometer).

distance = current odometer – previous odometer

Now enter the distance driven (in miles) and the amount of fuel it took to fill the tank (in gallons) into the first formula shown above to find your gas mileage (in MPG).

Are you interested in trying to improve your fuel efficiency? Try our fuel savings calculator to calculate how much you could save by improving your gas mileage, along with some easy tips on how to do it.