GasMileageCalc

MPG Calculator

Use the full-to-full method: fill the tank, drive, then fill up again. The fuel you pump on the second stop is what the trip burned. This tool shows the same result as US mpg, UK mpg, km/L and L/100km so you can compare figures from any source.

Fill-up details

Sample data

Full-to-full method: fill the tank, drive, fill again — the amount you pump is the fuel the trip used.

Your fuel economy

  • 30
    mpg
  • 36.03
    mpg
  • 12.75
    km/L
  • 7.84
    L/100km
300 miles ÷ 10 gal (US) = 30 US mpg
Same trip in metric terms: 7.84 L/100km. All four figures are the same trip expressed in different units.

Reading your result

US mpg divides miles by US gallons (3.785 L); UK mpg divides by the larger imperial gallon (4.546 L), so UK numbers run higher for the same car. L/100km expresses how many liters the trip takes per 100 km — lower is better there, while mpg is higher-is-better.

Results depend entirely on the numbers you enter. For a steadier average, record several fill-ups in a row and use the total distance and total fuel.

Next: turn your MPG into a trip fuel cost.