DemographicsGum Flat is approximately 141.86 square kilometres. In 2016 the population of Gum Flat was 213. The population is 53% male and 47% female. On average the monthly mortgage repayments in Gum Flat are $1000 to $1399. The most common weekly income bracket is $150 to $299 per week. Weekly rents in the area are on average $0 to $74.