The CO2 calculator is based on the ChoCO2 studies of GEIC, which calculate CO2 emissions from everyday Japanese electrical appliances and automobiles based on energy consumption figures. By marking the appliances you use and filling out the required information, you can get a quick idea of how you can impact on the environment through your lifestyle. The final calculation is based on the number of households in Japan, and points out how people impact on the environment as a collective force. Try adding and subtracting the various items to see what products tend to have larger impacts. The full study on which the calculations are based is available on the GEIC Homepage.