Fuel Savings Calculator

Reviewed by the CalculatorHub team, edited by James Graham. Method from US DOE fueleconomy.gov. Last verified 2026-06-23.

The Fuel Savings Calculator computes fuel savings from the relation annual savings = annual miles / old mpg x price - annual miles / new mpg x price. It takes 4 inputs (annual miles driven in miles, current vehicle fuel economy in mpg, new vehicle fuel economy in mpg, fuel price in USD per gallon) and returns the fuel savings. These calculators are for everyday drivers, rideshare and delivery operators, small fleet managers and home mechanics who want to plan the cost or range of a journey, compare one vehicle or driving habit against another for running cost, put a performance figure such as acceleration or engine output into usable terms, or check that a size or part suits the vehicle before money is spent. Enter your values below and the result updates instantly, and you can share a permalink that pre-fills the exact calculation. Keep every input in one measurement system before you calculate, since mixing miles with litres, US gallons with imperial gallons, or inches with millimetres will quietly skew the answer, and where a figure describes how your vehicle actually behaves, take it from your own recent records (odometer readings, fuel receipts, the numbers printed on the car itself) rather than the brochure. For example, with annual miles driven = 15000 miles, current vehicle fuel economy = 25 mpg, new vehicle fuel economy = 40 mpg, fuel price = 4 USD per gallon, the fuel savings works out to 900, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. The method is the standard form documented by US DOE fueleconomy.gov, and the figure above each result carries the date it was last verified. Where the result depends on how the vehicle is driven rather than on fixed numbers, as with fuel use, range and acceleration, expect the real figure to move with driving style, load, terrain, traffic, weather, tyre pressure and mechanical condition, and treat anything affecting fitment or safety, such as a change of tyre or wheel size, as something to confirm with the vehicle handbook or a qualified fitter before you commit.