MPG Calculator
Calculate your car's miles per gallon (MPG) fuel economy from miles driven and gallons used.
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How to use this tool
- Enter miles driven and gallons used in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your miles per gallon and the full breakdown beneath it.
Calculate your vehicle's fuel economy in miles per gallon.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
MPG = miles ÷ gallons
How it works
Miles per gallon (MPG) is the simplest measure of fuel economy: the total distance driven divided by the total volume of fuel consumed over that same distance.
The result is accurate as long as the odometer reading and fuel fill-up volume are measured correctly from the same start and end points; MPG varies with driving speed, load, terrain, and vehicle condition.
Worked example
Worked example — 300 miles on 10 gallons
- Miles driven = 300 mi; gallons used = 10 gal.
- MPG = 300 / 10 = 30 mpg.
Fuel economy = 30 mpg.
Common mistakes to avoid
- Calculating MPG from a single fill-up right after a long motorway run, which inflates the figure — average over several fill-ups for a realistic number.
- Resetting the odometer at fill but not recording the gallons precisely — rounded gallons cause significant percentage error at small quantities.
- Confusing US gallons (3.785 L) with Imperial gallons (4.546 L) when comparing MPG figures across countries.
Key terms
- MPG (miles per gallon)
- A measure of fuel economy expressing how many miles a vehicle travels on one US gallon of fuel; higher values indicate better efficiency.
- US gallon
- A unit of liquid volume equal to approximately 3.785 litres; used for fuel measurement in the United States.
- Fuel economy
- The efficiency with which a vehicle converts fuel energy into distance travelled; influenced by speed, driving style, vehicle weight, and aerodynamics.
- Fill-up method
- The standard way to measure real-world MPG: fill the tank to the brim, drive a known distance, refuel to the brim again, and divide miles by gallons used to refill.
- Odometer reading
- The distance displayed on a vehicle's odometer; used to determine miles driven between fill-ups when calculating MPG.
Frequently asked questions
- What is a good MPG?
- For a typical car, 30–40 MPG is considered good. Hybrids can exceed 50 MPG.