Driving Carbon Footprint Calculator

Burning one gallon of gasoline produces about 8,887 grams (8.887 kilograms) of carbon dioxide, a figure published by the U.S. Environmental Protection Agency. Divide your annual miles by your fuel economy to get gallons burned, then multiply by 8.887 kilograms to get annual tailpipe CO2 in kilograms, which converts to metric tons.

A gallon of gasoline contains carbon that, when burned, combines with oxygen to form CO2. Because CO2 molecules include the added oxygen, the mass of CO2 produced is much greater than the mass of fuel. The EPA's value of about 8,887 grams of CO2 per gallon reflects the carbon content of typical gasoline and complete combustion.

No. This is tailpipe (direct combustion) CO2 only, matching the EPA per-gallon factor. Producing and delivering the fuel adds further upstream emissions, and other greenhouse gases such as methane and nitrous oxide add a little more on a CO2-equivalent basis. The EPA greenhouse gas equivalencies resource covers these wider factors.

The two levers in this calculation are miles driven and fuel economy. Driving fewer miles, combining trips, carpooling, and choosing a higher-mpg or electric vehicle all cut gallons burned and therefore CO2. The U.S. fueleconomy.gov resource lets you look up the rated fuel economy for specific vehicles to use here.

An electric vehicle has no tailpipe CO2, so this gasoline-based calculation does not apply directly. Its footprint depends on the electricity used to charge it and the grid mix in your region. For an EV, use an electricity-based emissions calculation rather than the gasoline factor here.