Fuel Consumption Calculator
Calculate real gas mileage from odometer readings and gallons added, with MPG, gallons per 100 miles and L/100km.
Enter odometer readings and fuel added at each fill-up. The first row is the starting odometer reading, so fuel in that row is not counted.
Calculate Real Fuel Consumption
This page measures real fuel economy from fill-up records. For a US audience, the primary result is MPG, with gallons per 100 miles and L/100km shown for comparison.
- Enter the starting odometer reading in miles.
- At the next comparable fill-up, enter the new odometer reading and gallons added.
- Add more fill-ups to smooth out one-trip variation.
- Read the average MPG, gal/100 mi and metric L/100km equivalent.
Fuel Economy Formulas
Why Results Differ from EPA Ratings
- City traffic, cold starts and idling usually reduce real-world MPG.
- Highway speed, wind, hills, tire pressure and cargo load can change fuel use.
- Short fill-up intervals can amplify pump shutoff and rounding differences.
- Use several tanks when comparing seasons, routes or maintenance changes.
Frequently Asked Questions
Sources and References
- Fuel EconomyU.S. Department of Energy
- Find and Compare CarsU.S. Department of Energy
- Fuel Economy and Environment LabelU.S. EPA
Calculations are based on the listed reference sources. Links open in a new tab.
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Convert L/100 km to US mpg for fuel economy, fuel consumption, trip planning, vehicle comparisons, and efficiency checks.
Convert US mpg to L/100 km for fuel economy, fuel consumption, trip planning, vehicle comparisons, and efficiency checks.