The profitability of a lamb meat system is greatly influenced by lambing time. The most profitable lambing date optimises income from lamb meat and costs per hectare to produce it. It also involves labour availability and synergies with cropping systems and different pasture systems. This analysis does not include labour, and cropping and is only based on an annual pasture system. The base farm is located in Wagga Wagga. It is a single enterprise running a first cross ewe flock joined to terminal rams. It consists of annual rye grass and sub clover pasture. The base farm uses a July lambing system without production feeding. The system is run and validated and analysed using GrassGro® by overlaying several variables including lambing date from April to September, store lamb and finishing systems plus two grain and lamb prices. The analysis clearly shows that lambing in June on an annual based pasture with and without production feeding is the most profitable system. It optimises fecundity as a result of breeding season and fat score at joining, sale weight as a function of pasture utilisation and production feeding and minimal supplementary feeding of ewes. These results are based on a fixed sale date and sale weight.