Our carbon calculator estimates the amount of carbon dioxide your car puts in the air, based on your mileage and on the average MPG of your vehicle that you pluged in. Several assumptions underlie this calculation, so the final number is meant to be an estimate only.

Finally, we multiply the number of gallons of gas by 19.564 (for regular gasoline – diesel engines use a different factor of 22.91) to figure out how many pounds of carbon dioxide your car puts out. The resulting number might seem high – a typical car puts out many times its own weight in carbon dioxide every year. But remember that when fuel burns, it combines with oxygen in the air and becomes much heavier.

Our estimate may differ slightly from the estimates you find on other web sites. One reason for the discrepancy may be that some web sites include other greenhouse gases that your car creates in addition to carbon dioxide. Other reasons could be that we use slightly different assumptions about your driving habits, or slightly different fuel ratings for your car.

Factors used in the driving calculator:

• Gasoline: 19.564 lbs/gallon
• Diesel: 22.91 lbs/gallon
• Biodiesel: 4.582 lbs/gallon
• Compressed Natural Gas (CNG): 16.09 lbs/gallon
• Ethanol: 16.16 lbs/gallon