The Intergovernmental Panel on Climate Change (IPCC) has published guidelines for the development of national greenhouse gas-emissions inventories and recommendations for collecting data necessary to calculate greenhouse gas emissions. Many regional and local jurisdictions will be performing inventories of greenhouse gas emissions and estimating the benefits of mitigation strategies to reduce emissions. This article advocates the development of relational databases to calculate and store emissions estimates based on IPCC guidelines and quantities of precursors of greenhouse gases. Specific examples of tables and queries are used to illustrate calculation methods and formulae, the choice of database keys, and the choice of methods for joining tables to construct queries.