DemographicsBlack Mountain (NSW) is approximately 222.53 square kilometres. In 2016 the population of Black Mountain (NSW) was 310. The population is 53% male and 47% female. On average the monthly mortgage repayments in Black Mountain (NSW) are $1800 to $2399. The most common weekly income bracket is $400 to $499 per week. Weekly rents in the area are on average $0 to $74.