Gas Mileage (MPG) Calculator

Compute miles per gallon from distance and gallons used. Also returns L/100km.

Inputs

Result

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General calculation reads

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Scientific calculator (Casio fx-991EX)
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How to use this calculator

  • Fill up your tank, reset trip odometer.
  • Drive until next fill-up.
  • Enter the miles driven and gallons used to refill.

About this calculator

MPG is the standard US fuel-economy unit. Higher is better. Modern cars average 30-35 MPG combined; hybrids 45-55; large pickups 18-22. Outside the US, L/100km is more common — and the math is inverse: lower L/100km is better.

Frequently asked

Why does my displayed MPG differ from manual calculation?+
Onboard computers estimate based on injector pulses and air-flow sensors, often optimistic by 2-5%. Tank-to-tank manual is more accurate.
How do I convert MPG to L/100km?+
L/100km = 235.215 / MPG (approximately). Or convert through km and L as the calculator shows.
Why is highway MPG higher than city?+
Cruising at steady speed with momentum is more efficient than stop-and-go. Aerodynamic drag rises sharply above 60 mph though.
How can I improve my MPG?+
Properly inflated tires (+3%), smooth driving (+10-20%), reduce roof-rack drag, fix dirty air filter. The mpg-improvement-tips-calc estimates savings.
Is the EPA MPG accurate?+
Within 5-10% for most drivers. Real-world MPG depends heavily on terrain, traffic, AC use, and driving style.

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