The paper discusses EPA's available software for estimating landfill gas emissions. The software is based on a first-order decomposition rate equation using empirical data from U.S. landfills. The software provides a relatively simple approach to estimating landfill gas emission. The modeling methodology relies on a tiered approach where default data are used initially, and field test data for a specific landfill are developed and used to develop more accurate estimates. The paper gives an overview of the model and how it is used in the U.S. for determining applicability to national regulations and for developing estimates for emission inventories.