The population of Sudan in 2003 was estimated by the United Nations at 33,610,000, which placed it as number 33 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 40% under 15 years of age. There were 101 males for every 100 females in the country in 2003. According to the UN, the annual population growth rate for 2000–2005 is 2.17%, with the projected population for the year 2015 at 41,430,000. The population density in 2002 was 13 per sq km (34 per sq mi).
It was estimated by the Population Reference Bureau that 36% of the population lived in urban areas in 2001. The capital city, Khartoum, had a population of 2,628,000 in that year. Other major cities include Port Sudan, the only modern seaport, Wad Madani, Al Ubayyid, the principal city of central Sudan, and 'Atbarah. According to the United Nations, the urban population growth rate for 2000–2005 was 4.5%.