DemographicsSt Clair (Singleton - NSW) is approximately 48.77 square kilometres. In 2016 the population of St Clair (Singleton - NSW) was 5. The population is 0% male and 100% female. On average the monthly mortgage repayments in St Clair (Singleton - NSW) are $0 to $299. The most common weekly income bracket is $0 to $149 per week. Weekly rents in the area are on average $0 to $74.