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

Fuel Economy:

Cost per Mile
Learn how we calculated this below

On this page:

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

How to Calculate Gas Mileage

Fuel economy is often measured in miles per gallon, or mpg, in the US. It’s a measure of how efficiently a vehicle uses fuel. Improving fuel economy can reduce the cost of traveling the same distance.

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 can drive 100 miles using 6 gallons of gas.

fuel economy = 100 ÷ 6
fuel economy = 16.67 mpg

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

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

Start by filling up the tank in your vehicle completely. Make sure you record the odometer reading before you leave the gas station.

Then, drive as you normally would and use at least half the tank of gas before refilling.

At the gas station, record the new odometer reading. Then, fill up the tank and record the amount needed in gallons.

Find the distance driven by subtracting the previous odometer reading from the current reading.

distance = current odometer – previous odometer

Now, enter the distance and fuel to fill the tank into the formula above to find your gas mileage.

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 and get some easy tips to do so.