World Population Prospects - Population Division

World Population Prospects 2024

Glossary of Demographic Terms

Indicator	Topic	Definition
Age-specific fertility rates	Fertility	Number of births to women in a particular age group, divided by the number of women in that age group. The age groups used are: 15-19, 20-24, ..., 45-49. The data refer to annual civil calendar years from 1 January to 31 December.
Births	Fertility	Number of births over a given period. Refers to live births for annual civil calendar years from 1 January to 31 December. Data are presented in thousands.
Births by age group of mother	Fertility	Number of births over a given period classified by age group of mother (15-19, 20-24, 25-29, 30-34, ...45-49). Refers to live births for annual civil calendar years from 1 January to 31 December. Data are presented in thousands.
Child dependency ratio	Population	The ratio of the population under age x1 (e.g., 0-24) to the number of persons of working age x1-x2 (e.g., 25-64). It is expressed as number of dependants per 100 persons of working age (e.g., 25-64). Data are presented for different age categories.
Crude birth rate	Fertility	Number of births over a given period divided by the person-years lived by the population over that period. It is expressed as number of births per 1,000 population.
Crude death rate	Mortality	Number of deaths over a given period divided by the person-years lived by the population over that period. It is expressed as number of deaths per 1,000 population.
Deaths by sex	Mortality	Number of deaths over a given period. Refers to annual civil calendar years from 1 January to 31 December. Data are presented in thousands.
Deaths under age 5	Mortality	Number of deaths under age 5 over a given period. Refers to annual civil calendar years from 1 January to 31 December. Data are presented in thousands.
Feminity Ratio by broad age groups	Population	Number of Males per 100 Females by various functional combination of age groups (0-14, 0-17, primary and secondary school ages, 15-24, 15-49, ..., 18+, 50+, etc.). De facto population as of 1 July of the year indicated. Figures are expressed per 100 female population.
Infant Deaths, under age 1	Mortality	Number of deaths under age 1 over a given period. Refers to annual civil calendar years from 1 January to 31 December. Data are presented in thousands.
Infant mortality Rate	Mortality	Probability of dying between birth and exact age 1. It is expressed as deaths per 1,000 live births.
Life expectancy at birth	Mortality	The average number of years of life expected by a hypothetical cohort of individuals who would be subject during all their lives to the mortality rates of a given period. It is expressed as years.
Life expectancy at age x	Mortality	The average number of remaining years of life expected by a hypothetical cohort of individuals who already reached age x and would be subject during the remainder of their lives to the mortality rates of a given period. It is expressed as years.
Live births Surviving to Age 1	Population	Number of newborns in a given year who survive to the next calendar year, and reach their first birthday. This cohort survival measure is commonly used to plan for immunization programs. It is calculated as (B * (1-1q0)) + (B * (1q0 * 1a0)) where B is the number of live births, 1q0 is the probability of dying between birth and age 1, and 1a0 is the average time lived by those who died before reaching age 1. Data are presented in thousands.
Mean age at childbearing	Fertility	The mean age at childbearing is the mean age of mothers at the birth of their children if women were subject throughout their lives to the age-specific fertility rates observed in a given year.
Median age	Population	Age that divides the population in two parts of equal size, that is, there are as many persons with ages above the median as there are with ages below the median. It is expressed as years.
Mortality before age x	Mortality	The probability of dying between birth and exact age x measures the risk of premature death and is expressed as deaths under age x per 1,000 births.
Mortality between age x and x+n	Mortality	The probability that an individual alive at exact age x would die before exact age x+n, given the mortality conditions in a given year. For example, the probability of dying between exact age 15 and exact age 60 reflects mortality risks among adults and is expressed as deaths per 1,000 persons reaching age 15.
Natural Change	Population	Births minus Deaths. It is expressed as thousands.
Net migration	Migration	Net number of migrants, that is, the number of immigrants minus the number of emigrants. It is expressed as thousands.
Net migration rate	Migration	The number of immigrants minus the number of emigrants over a period, divided by the person-years lived by the population of the receiving country over that period. It is expressed as net number of migrants per 1,000 population.
Net reproduction rate	Fertility	The average number of daughters that female members of a birth cohort would bear during their reproductive life span if they were subject throughout their lives to the observed age-specific fertility and mortality rates of the given time period. It is expressed as the number of daughters per woman.
Old-age dependency ratio	Population	The ratio of the population aged x2 and over (e.g., 65+) to the number of persons of working age x1-x2 (e.g., 25-64). It is expressed as number of dependants per 100 persons of working age (e.g., 25-64). Data are presented for different age categories.
Old-age potential support ratio	Population	The ratio of the number of persons of working age x1-x2 (e.g., 25-64) to the population aged x2 and over (e.g., 65+). It is expressed as number of persons of working age x1-x2 (e.g., 25-64 years) per person aged x2 years or over (e.g., 65+). Data are presented for different age categories.
Percentage by broad age groups	Population	Percentage of Total Population by various functional combination of age groups (0-14, 0-17, primary and secondary school ages, 15-24, 15-49, ..., 18+, 50+, etc.). De facto population as of 1 July of the year indicated. Figures are expressed per 100 population.
Percentage rural	Population	Rural population as a percentage of the total population.
Percentage urban	Population	Urban population as a percentage of the total population.
Population	Population	De facto population in a country, area or region as of 1 January or 1 July of the year indicated. Figures are presented in thousands.
Population annual doubling time	Population	The population doubling time corresponds to the number of years required for the total population to double in size if the annual rate of population change would remain constant. It is calculated as ln(2)/r where r is the annual population growth rate. Doubling time is computed only for fast growing populations with growth rates exceeding 0.5 per cent.
Population by broad age groups	Population	De facto population as of 1 July of the year indicated classified by sex (male, female, both sexes combined) and by various functional combination of age groups (0-14, 0-17, primary and secondary school ages, 15-24, 15-49, ..., 18+, 50+, etc.). Data are presented in thousands.
Population by five-year age group and sex	Population	De facto population as of 1 July of the year indicated classified by sex (male, female, both sexes combined) and by five-year age groups (0-4, 5-9, 10-14, ..., 95-99, 100+). Data are presented in thousands.
Population by sex	Population	De facto population as of 1 July of the year indicated classified by sex (male, female, both sexes combined). Data are presented in thousands.
Population change	Population	Population increment over a period, that is, the difference between the population at the end of the period and that at the beginning of the period. Refers to annual civil calendar years from 1 January to 31 December. Data are presented in thousands.
Population density	Population	Population per square Kilometer.
Population growth rate	Population	Average exponential rate of growth of the population over a given period. It is calculated as ln(P2/P1)/n where P1 and P2 are the populations on 1 January of subsequent years, and n is the length of the period between t1 and t2 (n=1 for annual data). It is expressed as a percentage.
Population sex ratio	Population	Number of males per 100 females in the population.
Rate of Natural Change	Population	Crude birth rate minus the crude death rate. Represents the portion of population growth (or decline) determined exclusively by births and deaths. It is expressed as number of births per 1,000 population.
Rural population	Population	De facto population living in areas classified as rural (that is, it is the difference between the total population of a country and its urban population). Data refer to 1 July of the year indicated and are presented in thousands.
Sex ratio at birth	Fertility	Number of male births per 100 female births.
Sex Ratio by broad age groups	Population	Number of Females per 100 Males by various functional combination of age groups (0-14, 0-17, primary and secondary school ages, 15-24, 15-49, ..., 18+, 50+, etc.). De facto population as of 1 July of the year indicated. Figures are expressed per 100 male population.
Total dependency ratio	Population	The ratio of the sum of the population under age x1 (e.g., 0-24) and that aged x2 and over (e.g., 65+) to the number of persons of working age x1-x2 (e.g., 25-64). It is expressed as number of dependants per 100 persons of working age (e.g., 25-64). Data are presented for different age categories.
Total fertility rate	Fertility	The average number of live births a hypothetical cohort of women would have at the end of their reproductive period if they were subject during their whole lives to the fertility rates of a given period and if they were not subject to mortality. It is expressed as live births per woman.
Under-five Mortality Rate	Mortality	Probability of dying between birth and exact age 5. It is expressed as deaths per 1,000 births.
Urban population	Population	De facto population living in areas classified as urban according to the criteria used by each area or country. Data refer to 1 July of the year indicated and are presented in thousands.
Women aged 15-49	Fertility	Number of women aged 15-49 as of 1 July of the year indicated, and that number as a percentage of the total female population as of 1 July of the year indicated. The number of women is presented in thousands.

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