Gas Mileage Calculator
Calculate vehicle fuel economy in Miles Per Gallon (MPG) from miles driven and US gallons of fuel consumed.
Calculator Inputs
Total distance driven. Must be a positive number.
Total fuel consumed, in US gallons. Must be a positive number.
- Fuel Economy (MPG)
- 30.00
About these results
CalcSpectrum calculators produce automated estimates using established formulas and the specific values you enter. Because real-world outcomes depend on input accuracy, mathematical assumptions, and rounding conventions, please verify critical figures with an appropriately qualified financial, tax, medical, legal, or other professional, as relevant.
How It's Calculated
Formula
This calculator computes vehicle fuel economy in Miles Per Gallon (MPG): the distance driven divided by the fuel consumed. Fuel is measured in US gallons — not Imperial gallons, which are about 20% larger — so results are only comparable to other US-gallon MPG figures. Enter the total miles driven and the total US gallons of fuel consumed over that distance to get the resulting MPG.
Worked Examples
300 miles on 10 US gallons
- MPG = 300 / 10 = 30 MPG.
Frequently Asked Questions
Is this US gallons or Imperial gallons?
US gallons. One US gallon is about 3.785 liters, while an Imperial gallon is about 4.546 liters — roughly 20% larger. Using an Imperial-gallon fuel amount here will produce an MPG figure that is too low compared to standard US MPG ratings.
Why is my MPG lower than the vehicle's rated MPG?
EPA-rated MPG comes from standardized test cycles. Real-world MPG varies with driving style, traffic, terrain, weather, and vehicle load, so it commonly differs from the window-sticker rating.
Can I use this for metric units (km and liters)?
Not directly. This calculator's formula and inputs are in miles and US gallons. Convert km to miles and liters to US gallons before entering values if you need a metric-sourced result.