Automotive & Engines
Basic

Miles Per Gallon

Distance in miles per gallon of fuel.

Formula

MPG=dFMPG = \frac{d}{F}

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Variables

MPGMiles per gallon
dDistance (mi)
FFuel (gal)

Example

300 mi on 10 gal: MPG = 30

How it works

Miles per gallon measures how far a vehicle can travel for each gallon of fuel it uses. The formula works by dividing the total distance driven by the number of gallons consumed, so the result tells you the average distance covered per unit of fuel. A higher MPG means the vehicle is more fuel-efficient because it goes farther on the same amount of fuel.

When to use it

Use this when you want to compare fuel economy for a car, truck, or motorcycle, or to estimate how efficiently a trip used fuel. It is also useful for checking whether one vehicle is more economical than another.

Worked example, step by step

A car drives 240 miles and uses 8 gallons of fuel. MPG = d / F MPG = 240 / 8 MPG = 30 So the car gets 30 miles per gallon.

Common mistakes to avoid

  • Dividing gallons by miles instead of miles by gallons
  • Using the wrong units, such as kilometers without converting to miles
  • Forgetting that MPG is an average over a trip, not necessarily the fuel use at every moment

Did You Know?

A US gallon is about 20% smaller than an imperial gallon, so US and UK mpg figures aren't comparable.

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Reviewed & maintained by the FormulaWon editorial teamLast reviewed September 2026