Free tool
Gas mileage (MPG) calculator
Fill the tank, reset the trip meter, and fill again. Enter the miles and the gallons it took.
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How it works
How it works
MPG = miles driven divided by gallons used. Gallons per 100 miles is the reverse view. Add the price per gallon to see the cost per mile.
Example: 300 miles on 10 gallons is 30 miles per gallon, or 3.33 gallons per 100 miles. At $3.50 a gallon the fuel cost is $35.00, or about 11.7 cents a mile. Measure over several fill-ups for a steadier number, since a single tank can be skewed by how full the pump left it.
FAQ
About this calculator
How do I measure MPG?
Fill the tank, note the odometer, drive, then fill again. Divide the miles by the gallons added.
Why does it change?
Speed, traffic, weather, load and tire pressure all affect fuel use.
Is the dashboard number accurate?
It can be off by a little. Measuring a full tank to a full tank is usually closer.
Is anything saved?
No. The math runs in your browser and nothing you enter is sent to us.
Read the guide: How to Figure Gas Mileage and Trip Fuel Cost. See all free tools. More free tools: Square footage calculator, Flooring and tile calculator, Length converter, or see all free tools.
General information, not tax or legal advice. How we write and check our tools.