MPG Calculator

Measure your car's fuel economy from the miles driven on a tank and the fuel it took to refill.

How the Math Works

The MPG Calculator uses a straightforward mathematical formula to determine fuel efficiency: Miles Per Gallon (MPG) equals the total miles traveled divided by the total gallons of fuel consumed. This calculation, expressed as mpg = miles ÷ gallons, provides a direct measure of how many miles your vehicle can travel using one gallon of gasoline. The formula requires two basic measurements - distance traveled and fuel used - making it one of the simplest yet most practical calculations in automotive mathematics.

Practical Applications

To use this calculator effectively, simply enter the total distance you've traveled in miles and the total amount of fuel consumed in gallons. For most accurate results, use the same units throughout your calculation and record your odometer reading before and after your trip, along with the exact amount of fuel used. You can apply this calculation to individual tank fills for short-term efficiency tracking or to multiple fill-ups over time for a more comprehensive average of your vehicle's fuel performance.

Day-to-Day Use

Understanding your vehicle's MPG helps you make smarter financial decisions about driving habits and vehicle maintenance. By tracking this metric regularly, you can identify when your engine needs service, detect potential fuel leaks or mechanical issues, and choose the most fuel-efficient routes for your daily commutes. Additionally, knowing your vehicle's real-world MPG helps when comparing different models before purchasing, potentially saving you hundreds of dollars annually in fuel costs.

Worked example

350 mi on 12 gal → 29.2 mpg (≈8.06 L/100km).

FAQ