The size of Nilgen is approximately 255 square kilometres. It has 8 parks covering nearly 23% of total area. The population of Nilgen in 2011 was 388 people. By 2016 the population was 231 showing a population decline of 40.5% in the area during that time. The predominant age group in Nilgen is 50-59 years. Households in Nilgen are primarily childless couples and are likely to be repaying $2400 - $2999 per month on mortgage repayments. In general, people in Nilgen work in a labourer occupation. In 2011, 86.8% of the homes in Nilgen were owner-occupied compared with 92.1% in 2016. Currently the median sales price of houses in the area is $360,000.