Gas Mileage Calculator
Calculate your car's actual miles-per-gallon from a fill-up.
Enter your numbers and select Calculate to see results.
About This Calculator
This calculator computes your vehicle's real-world fuel economy in miles per gallon (MPG), based on the miles you drove and the gallons of fuel used to cover that distance — useful for tracking whether your car is performing as expected or comparing against the EPA-estimated rating.
How This Is Calculated
MPG = Miles Driven ÷ Gallons Used
Driving 300 miles on 10 gallons gives 30 MPG.
Assumptions
- Assumes the gallons entered fully filled the tank from empty to the point where miles were measured.
Frequently Asked Questions
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Last updated January 15, 2026. Results are estimates for informational purposes only — read our disclaimer.