Not too long ago, the concept of a Carbon Footprint was a foreign one. But as global climate change theory has gained traction in the general public, carbon footprint has become common lingo. Online calculators which account for ones personal carbon emissions have emerged as a popular tool for the climate-minded to track and reduce their greenhouse gas emissions. These calculators are so prevalent that if you search Google, you’ll find a wide selection waiting for your personal energy and transportation data. Here’s the problem though: not all carbon footprint calculators are created equal. So to help you parse out the good from the bad, and assess the accuracy of a quick and dirty approach, I tested nine different calculators.