The size of Castlereagh is approximately 32.1 square kilometres. It has 6 parks covering nearly 0.6% of total area. The population of Castlereagh in 2011 was 1,054 people. By 2016 the population was 1,188 showing a population growth of 12.7% in the area during that time. The predominant age group in Castlereagh is 50-59 years. Households in Castlereagh are primarily couples with children and are likely to be repaying over $4000 per month on mortgage repayments. In general, people in Castlereagh work in a clerical occupation. In 2011, 79.5% of the homes in Castlereagh were owner-occupied compared with 79.1% in 2016. Currently the median sales price of houses in the area is $2,755,000.