This calculator compares two MPG figures — your current vehicle against a prospective upgrade, or simply two numbers you want to compare — and shows how much fuel and money you'd save each year at your actual driving distance and local gas price.
How the Fuel Savings Calculator works
The calculator converts each MPG figure into annual gallons consumed by dividing your annual mileage by that MPG value. It then multiplies the difference in gallons by your entered gas price to get the annual dollar savings. This mirrors how you actually pay for fuel: at the pump, in dollars per gallon, not per mile.
Inputs and what they mean
Current MPG and New MPG are the two fuel-economy figures you're comparing — these can be two vehicles, two trims, or your fill-up MPG before and after a repair. Annual Miles should reflect your real driving pattern (commute plus errands plus road trips), since savings scale directly with distance. Gas Price should be your local current price; the calculator does not forecast future price changes.
Limits and edge cases
This calculator assumes constant annual mileage and a flat gas price — it will not capture years where you drive unusually more or less, or periods of sharp fuel-price swings. It also does not account for the purchase cost, financing, insurance, or maintenance differences between two vehicles; for a full cost comparison, pair this with a vehicle ownership-cost tool. For electric vehicles, use the Gas vs Electric calculator instead, since electricity is priced per kWh, not per gallon.