Agriculture in Australia contributed 15.5% of total national greenhouse gas (GHG) emissions produced in 2009, mainly as methane (CH4) and nitrous oxide (N2O). In this study, a new tool (Feedlot greenhouse gas accounting framework also known as F-GAF) incorporating all components of the GHG emissions produced from feedlot systems was demonstrated. The objective of developing the F-GAF was to create awareness of the various sources of GHG emissions from feedlots in order to stimulate thinking and action aimed at reducing these emissions while further improving farming efficiency. It was found that the main source of total GHG emissions was CH4 from enteric fermentation, contributing around 60% of the total emissions. The N2O emissions were mainly produced from manure and contributed 30% of the total emissions. The F-GAF can be used as a practical tool to calculate GHG emissions from feedlot systems. Further studies can be conducted to incorporate mitigation options into the tool.