DemographicsFlagstaff is approximately 3.75 square kilometres. In 2016 the population of Flagstaff was 87. The population is 51% male and 49% female. On average the monthly mortgage repayments in Flagstaff are $1000 to $1399. The most common weekly income bracket is $400 to $499 per week. Weekly rents in the area are on average $150 to $199.