Two odometer readings and one receipt
Everything is computed in your browser. Nothing is sent anywhere — this page has no analytics and no trackers.
Questions
What is the formula for MPG?
Miles driven divided by gallons used. Miles driven is the current odometer reading minus the reading at your last fill-up; gallons used is what you just put in to fill the tank back up.
Why is my dashboard MPG different?
Dashboard readouts estimate fuel used from injector timing rather than measuring it, and they are commonly optimistic by a few percent. Two odometer readings and a pump receipt measure what actually happened.
Does this work if I only part-filled the tank?
Not on its own. A partial fill leaves an unknown amount in the tank, so carry the gallons forward and divide at the next full tank — that covers both fills at once.
The long version
This tool is the arithmetic on its own. How to calculate MPG by hand is the explanation behind it — the full-tank rule, why dashboards read high, and how to handle partial fill-ups.