As the Memorial Day Weekend approaches, many of us are planning road trips — according to the American Automobile Association (AAA), over 30 million Americans will get in their personal vehicles for a weekend get-away, with many Driving hundreds of miles.

Although gas prices have dropped slightly during the past few weeks, they are still a dollar per gallon higher than they were one year ago at this time. These prices have made many of us think hard about the efficiency of our vehicles — how much is it costing us to drive?

We have developed a tool to help you determine the costs of driving your car or truck, including how much carbon dioxide (CO2) your vehicle produces. Carbon dioxide is a key greenhouse gas that is contributing to global warming. Using the tool below, select your state, your car’s gas mileage, and how many miles you drive in a typical year (default values are set to national averages).

This widget — which you are welcome to embed on your webpage — also displays the CO2 emissions that result from a particular amount of driving. Gas price data are automatically updated daily from the AAA.