⛽ MPG Calculator
Enter the miles you drove and the gallons you used, and see your true miles per gallon — with the L/100km and km/L equivalents alongside it.
🚗 Measure Your Fuel Economy
⛽ Fuel economy for 300 miles on 12.0 gal
What is an MPG Calculator?
It turns two numbers you already have — the miles on your trip meter and the gallons at the pump — into a clear picture of how efficiently your car uses fuel. Miles per gallon is the headline figure most US drivers track, and watching it tank to tank is the quickest way to spot a problem or prove a fix worked.
Because the same efficiency can be written three ways, the tool also shows litres per 100 km and kilometres per litre, so you can line your car up against European ratings or a rental abroad without reaching for a conversion chart.
❓ Frequently Asked Questions
How does the MPG calculator work?
Enter the miles you covered on a tank and the number of gallons it took to fill back up, and the calculator divides miles by gallons to give your miles per gallon. It also shows the same figure as litres per 100 km and kilometres per litre so you can compare against metric ratings.
What is the most accurate way to measure MPG?
Fill the tank completely, reset your trip meter, drive normally until you are ready to refuel, then fill up completely again. The trip meter gives the miles and the pump shows the gallons added — that pair is your true, real-world economy for that stretch of driving.
Why is my real MPG lower than the window sticker?
EPA and manufacturer figures come from controlled test cycles. Cold weather, short trips, heavy loads, aggressive acceleration, under-inflated tires, and highway speeds above 60 mph all pull real-world economy below the rated number, sometimes by 20% or more.
How do I convert MPG to L/100km?
Divide 235.2 by your US MPG. For example, 30 MPG is about 7.84 L/100km. The calculator does this for you and also reports km/L, which is MPG multiplied by roughly 0.425.