No comprehensive census based upon systematically sound methods has ever been taken in Afghanistan. Most population statistics rely on estimates and samples. Successive governments have manipulated figures for their own political objectives. UN agencies, hundreds of NGOs, as well as bilateral agencies use different figures to suit their purposes in designing assistance programs. Furthermore, instability caused by the Soviet-Afghan war and the consequent civil war resulted in massive movements of uprooted peoples. These factors also make demographic sampling necessarily imprecise.

The most scientific demographic survey carried out in Afghanistan was also one of the first. Conducted in 1972-74 by the State University of New York for the United States Agency for International Development, in cooperation with the Afghan government, this survey reported a settled population of 10.18 million. It did not cover the entire nation, and the nomadic population was not surveyed. The nomads were separately around at slightly more than 1.1 million.

2001 population estimate was 26,813,000, though the effect of the war—with its casualties and refugees—makes estimating difficult.In 2000 some 80 % of the population lived in rural areas. Of the urban dwellers, likely about half lived in Kabul, the capital city. The nomadic population was around to be about 2.5 million people. During the war with the Soviets the number of Afghan refugees outside the nation escalated dramatically, with as many as 2.7 million to 3 million refugees in Pakistan and another 1.6 million in Iran. About 150,000 Afghans were able to migrate permanently to other countries, including the United States, Australia, India and various European countries.