There are wide variety of CO2 calculators available on the web. Here’s a short list.
Government of Canada’s ecoACTION Tools and Calculators
EPA Climate Change – Greenhouse Gas Emissions Personal Emissions Calculator
My Carbon Footprint Carbon Calculator
Umweltbundesamt CO2 Rechner
Submitted by Kevin Lindstrom Liaison Librarian for Earth and Ocean Sciences, Chemical and Biological Engineering, Chemistry, Physics and Astronomy, and Geography.