The main sources of GHG emitted on dairies consist of enteric CH₄ production, N₂O production from housing, and both CH₄ and N₂O production from manure management systems. The US greenhouse gas (GHG) inventory estimates that dairy production comprises 37% of total enteric methane (CH₄) emitted as well as 52% and 34% of the total CH₄ and nitrous oxide (N₂O) emitted from manure management, respectively, making it an important sector of agricultural GHG emissions. Confined dairy production systems typically consist of cattle housed either in barns or open-lots with the manure intensively managed in a variety of systems. While enteric CH₄ production is one of the main sources of GHG generated on farms, depending on the manure management strategies employed, manure derived GHG can exceed that of enteric CH₄ production. On farm data collected from different housing types and manure management strategies in the western US reported daily CH₄ production rates ranging from 0.75 to 1.72 kg/animal unit (AU), with the majority of emissions from the cattle housing during the cold months and from the manure management system in the warmer months. Emissions of N₂O from the production facilities were lower at approximately 200 g/AU per day, with the majority from the housing area. Current inventory methods tend to either over or underestimate on farm emissions depending on the climatic region and time of year. This underscores the importance of obtaining annual on farm data when comparing on farm emissions to inventory estimates. Improvements in the inventory calculations via validation with on-farm measurements and modeling need to be done to improve these methodologies to accurately quantify emissions from this sector.