DemographicsMount Napier is approximately 32.51 square kilometres. In 2016 the population of Mount Napier was 17. The population is 63% male and 38% female. On average the monthly mortgage repayments in Mount Napier are $3000 to $3999. The most common weekly income bracket is $300 to $399 per week. Weekly rents in the area are on average $0 to $74.