With the abolition of EU milk quotas in 2015, the Irish dairy sector is positioning itself for substantial expansion which will result in an increase in calves from the dairy herd available for beef production. A wide range of beef cattle production systems are possible for these extra calves reflecting differences in breed, gender and finishing age. The Grange Dairy Beef Systems Model was used to simulate beef production from male and female calves born to Holstein-Friesian dairy cows bred to late maturing, early maturing and Holstein-Friesian sires and finished at different ages. The most profitable system was finishing steers at 28 months of age with the least profitable system being finishing male animals as bulls at 16 months of age. All systems were sensitive to beef, calf and concentrate price variations. The main implications from this study are that, irrespective of the system, maximising the proportion of grazed grass in the diet and the percentage of live weight gain from grass while also maintaining a high carcass output per hectare are the main drivers of profitability. Other issues such as land and labour charges, bonus schemes and variations in beef, calf and concentrate prices are important and can differ considerably depending on farm circumstances. Therefore, these issues need to be considered when deciding between different dairy calf-to-beef systems.