MPG Calculator — Find Your Real Fuel Economy

Track your real fuel economy, not the sticker. Enter the miles you drove on a tank and the gallons it took to fill back up, and we’ll give you your actual MPG and its metric equivalent.

How this calculator works

MPG is just miles driven divided by gallons used. The trick is measuring it right: fill the tank fully, reset your trip meter, drive a normal mix of roads, then refill to the same click-off point and read the pump’s gallons. We also convert to L/100km, the rest of the world’s standard.

What changes the number

Measure over a full tank, not a short trip — short samples are noisy.
Always fill to the same point (first auto-shutoff) both times, or the gallons figure is off.
Average two or three tanks for a number you can trust across seasons.

Frequently asked questions

Why is my MPG worse than the EPA rating?

EPA tests are run in controlled conditions. Cold weather, short trips, heavy loads, aggressive acceleration, and highway speeds over 70 mph all pull real-world economy below the sticker.

What’s a good MPG?

It depends on the vehicle. A modern sedan often does 30–40 mpg combined, a hybrid 45–55, a pickup or SUV 18–25. Compare against the same class, not across classes.

How do I convert MPG to L/100km?

Divide 235.2 by your MPG. So 30 mpg ≈ 7.8 L/100km. Our MPG ⇄ L/100km converter does it both ways.