This report documents the development of a spreadsheet tool designed to help the California Air Resources Board (CARB) estimate total reductions in emissions of greenhouse gases (GHGs) for various climate-change mitigation strategies being considered by CARB. The spreadsheet tool is called the California Air Resources Board Climate Change Mitigation Strategy Impact Calculator, or CARB CCM Calculator for short. The CARB CCM Calculator estimates reductions in CO2-equivalent (CO2e) emissions of GHGs in a user-specified target year and over a user-specified period of years, for each climate-change mitigation strategy. The CARB CCM Calculator estimates reductions for the following mitigation strategies: Cargo-Handling Equipment Anti-Idling, Low-GWP Refrigerants for Mobile Vehicle Air Conditioning Systems, Cool Automobile Paints, Low-friction Engine Oil, High GWP Reduction from Stationary Sources, Alternative Suppressants in Fire Protection systems, and Foam Recovery and Destruction Program.