About Gas Mileage Calculator
Track actual vehicle gas mileage using odometer fillup readings. Computes realized MPG, km/L, and L/100km, highlights percentage deviations from manufacturer EPA window stickers, and estimates total full-tank driving range.
Key Capabilities & Features
- Accurate tank-to-tank fillup calculation from starting and ending odometer readings
- Computes realized MPG, km/L, and L/100km
- Automated variance comparison against EPA/WLTP manufacturer window sticker rating
- Full-tank driving range projection based on fuel tank capacity
How to Use Gas Mileage Calculator
Record Starting Odometer
Enter the vehicle odometer reading from your previous full tank fillup.
Record Ending Odometer
Enter current odometer reading at the gas station.
Enter Fuel Added
Input exact gallons or liters pumped to top off the tank.
Review Realized Efficiency
See your true MPG or L/100km and variance from factory ratings.
Privacy & In-Browser Execution Guarantee
100% client-side calculation. Your data never leaves your browser.
Frequently Asked Questions
Why does my real mileage differ from the EPA sticker?
EPA window stickers reflect lab tests under idealized conditions. Aggressive acceleration, cold weather, roof racks, and city stop-and-go traffic typically decrease mileage by 10-25%.
What is the most accurate way to calculate car mileage?
The tank-to-tank method: Fill the tank completely, reset trip odometer, drive normally, and at the next full fillup divide the trip miles by the gallons added.