DemographicsUpper Flagstone is approximately 29.76 square kilometres. In 2016 the population of Upper Flagstone was 171. The population is 52% male and 48% female. On average the monthly mortgage repayments in Upper Flagstone are $1400 to $1799. The most common weekly income bracket is $650 to $799 per week. Weekly rents in the area are on average $0 to $74.