The population of Tonga in 2003 was estimated by the United Nations at 104,000, which placed it as number 178 in population among the 193 nations of the world. In that year approximately 4% of the population was over 65 years of age, with another 41% of the population under 15 years of age. There were 103 males for every 100 females in the country in 2003. According to the UN, the annual population growth rate for 2000–2005 is 0.97%, with the projected population for the year 2015 at 115,000. The population density in 2002 was 135 per sq km (349 per sq mi). However, only 45 of the nation's 171 islands are inhabited.
It was estimated by the Population Reference Bureau that 38% of the population lived in urban areas in 2001. The capital city, Nuku'alofa, had a population of 37,000 in that year. The city is on the island of Tongatapu, where two-thirds of the population resides. According to the United Nations, the urban population growth rate for 2000–2005 was 1.7%.