Data Sources

A description of the empirical data used and the methods applied in revising past estimates of population and components of demographic change (fertility, child, adult and overall mortality, international migration) is available here for each country or area for the period 1950 to 2021. For the countries with less than 1,000 inhabitants in 2021, only the data sources for total population are made available.

Select below a country or area to see the respective information, or download the whole set of metadata in PDF format for all countries or areas or a tabular version for each demographic component under Documentation.


Population: Total population and distribution by age and sex estimated to be consistent with the population by age and sex of the (a) 2011 Census; (b) official estimates through 2021; (c) International estimates used up to 2019; and with estimates of the subsequent trends in fertility, mortality and international migration.

Fertility: Total fertility rate and age pattern of fertility based on: (a) official estimates of age-specific fertility rates through 2021; (b) registered births classified by age of mother and the underlying female population by age through 2020; (c) adjusted for underregistration; (d) International estimates used up to 2019.  In addition, the indirect estimates obtained from the application of the reverse survival method to the 1978-2010 Education Stats and 2011 Census have been considered.

Child Mortality: Under-five mortality based on: (a) official estimates of infant and child mortality through 2018; (b) registered infant and child deaths through 2021.

Overall Mortality: Life expectancy at birth and age pattern of mortality based on: (a) official estimates through 2018; (b) registered deaths by age and sex available through 2021; (c) mortality rates for older ages were adjusted; (d) International estimates used up to 2021.

Migration: International migration based on: (a) estimates of migrant flows, and assumed subsequent trends in international migration; (b) information on foreign-born populations from censuses and registers from major countries of destination; (c) estimates derived as the differences between overall population growth and natural increase; (d) UNHCR statistics on the number of refugees in the main countries of asylum.

Disclaimer: This web site contains data tables, figures, maps, analyses and technical notes from the current revision of the World Population Prospects. These documents do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.