The population of Sierra Leone in 2003 was estimated by the United Nations at 4,971,000, which placed it as number 111 in population among the 193 nations of the world. In that year approximately 3% of the population was over 65 years of age, with another 44% of the population under 15 years of age. There were 96 males for every 100 females in the country in 2003. According to the UN, the annual population growth rate for 2000–2005 is 3.80%, with the projected population for the year 2015 at 6,399,000. The population density in 2002 was 78 per sq km (203 per sq mi). The Sierra Leone Peninsula is the most densely populated region of the country.
It was estimated by the Population Reference Bureau that 37% of the population lived in urban areas in 2001. The capital city, Freetown, had a population of 822,000 in that year. According to the United Nations, the urban population growth rate for 2000–2005 was 4.0%. Other main towns are Koindu, Bo, Kenema, and Makeni.
The prevalence of AIDS/HIV has had a significant impact on the population of Sierra Leone. The United Nations estimated that 7% of adults between the ages of 15–49 were living with HIV/AIDS in 2001. The AIDS epidemic causes higher death and infant mortality rates, and lowers life expectancy.