DemographicsHorsham is approximately 23.83 square kilometres. In 2016 the population of Horsham was 14543. The population is 48% male and 52% female. On average the monthly mortgage repayments in Horsham 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.