The size of Birriwa is approximately 77.3 square kilometres. The population of Birriwa in 2011 was 365 people. By 2016 the population was 47 showing a population decline of 87.1% in the area during that time. The predominant age group in Birriwa is 60-69 years. Households in Birriwa are primarily childless couples and are likely to be repaying $1400 - $1799 per month on mortgage repayments. In general, people in Birriwa work in a managers occupation. In 2006, 31.1% of the homes in Birriwa were owner-occupied compared with 83.2% in 2011.