Fuel economy is simply how far you go on a unit of fuel.
Where
| Distance | Miles driven |
| Fuel used | Gallons consumed |
Worked example
Driving 300 miles on 12 gallons gives 300 ÷ 12 = 25 MPG.
FAQ
Does this formula give city or highway fuel economy? It calculates whatever trip data you enter, so feeding in city driving distance and fuel used gives city-cycle economy, while highway trip data gives highway economy, since the formula itself doesn’t distinguish driving conditions. Keeping several fill-ups in a simple log makes trends easier to spot than judging fuel economy from any single tank.
Why does my calculated MPG differ from what my dashboard shows? Dashboard fuel economy estimates use the vehicle’s own sensors and algorithms, which can differ from a manual tank-to-tank calculation due to sensor calibration, partial fill-ups, or averaging over a different distance window.
Use the Fuel Economy Calculator for all units at once.