Last updated: July 12, 2026
Demographer.org combines national and international demographic datasets to present country-level population profiles. This page explains how the principal indicators are selected, interpreted and displayed.
Population
Population refers to the number of people covered by the definition used in the cited source. Depending on the country, the figure may represent a census count, registered population, resident population, de facto population or model-based estimate.
The reference date is important. A population reported on January 1 is not directly identical to a mid-year estimate for the same calendar year.
Population growth
Annual population growth describes the percentage change in population over a stated period. Growth can reflect births, deaths and net migration.
When a source supplies an official growth rate, that rate is preferred. Otherwise, a rate may be calculated from two population totals using a standard annual growth formula. Calculated values should be identified as calculations rather than official published rates.
Fertility
The total fertility rate estimates the average number of children a woman would have if the age-specific fertility rates observed in a stated period remained constant throughout her reproductive years.
It is a period indicator, not a count of children already born to an average woman. It may be derived from vital registration, surveys, censuses or demographic models.
A fertility rate near 2.1 births per woman is often used as a broad replacement-level reference in low-mortality populations. Actual replacement level varies with mortality and other population conditions.
Birth and death indicators
The crude birth rate measures live births per 1,000 people during a stated period. The crude death rate measures deaths per 1,000 people.
These rates are affected by population age structure. A country with an older population can have a relatively high crude death rate even when health conditions and life expectancy are favorable.
Life expectancy
Life expectancy at birth estimates the average number of years a newborn would live if the mortality rates observed during the reference period remained constant throughout life.
It is a summary measure based on current mortality conditions. It is not a prediction of the exact lifespan of a child born during that year.
Age structure
Age structure is normally presented using three broad groups:
- Ages 0–14: children and younger adolescents
- Ages 15–64: the broad working-age population
- Ages 65 and older: the older population
These groups support broad comparison but do not represent identical education, employment or retirement boundaries in every country.
Age shares may not total exactly 100 percent because of rounding, unknown ages or source-specific classifications.
Median age
Median age divides the population into two equal groups: half of the population is younger than the median and half is older.
It should not be confused with average age. Median age is influenced by fertility, mortality, migration and the age structure inherited from earlier generations.
Dependency ratios
Age dependency ratios compare populations commonly treated as dependent age groups with the broad working-age population. The most common calculation compares ages 0–14 and 65 or older with ages 15–64.
This is a demographic measure rather than a direct count of economically dependent people. Many people outside working ages are economically active, while some people within working ages are not employed.
Migration
Net migration is the difference between the number of people entering and leaving a country during a stated period. A positive figure indicates more arrivals than departures, while a negative figure indicates more departures than arrivals.
Migration is one of the most difficult demographic components to measure. Sources may use border records, residence permits, population registers, surveys, censuses or demographic balancing methods.
Net migration estimates from different sources should not be combined unless their periods and definitions are compatible.
Urbanization
The urban population share represents the proportion of people living in areas classified as urban by the source.
Definitions of “urban” vary among countries. They may depend on administrative status, population size, density, infrastructure or economic activity. International comparisons should therefore be interpreted with care.
Population density
Population density is generally calculated as population divided by land area. Sources may differ in whether inland water, disputed territory or overseas areas are included.
National density does not describe how evenly people are distributed within a country. A country can have a low national density while containing highly concentrated metropolitan regions.
Historical series
Historical population values may be revised after a new census, a change in territorial boundaries or the release of a reconstructed demographic series.
A table can therefore differ from an older edition even for years that have already passed. Revised historical values are used when the updated source provides a more consistent series.
Population projections
Projection tables describe future scenarios based on assumptions about fertility, mortality and migration. They are not forecasts with guaranteed outcomes.
Demographer.org normally uses the central or medium projection variant when one general series is required. Other variants may be shown when they materially affect the interpretation.
The projection base year, variant and source should be identified. Projected values should remain visually separate from observed and estimated historical figures.
Source comparison
National and international totals may differ because they are designed for different purposes. A national authority may publish the most current administrative total, while an international organization may use a harmonized mid-year series designed for comparison across countries.
The selected source should match the purpose of the indicator. Country-specific sections may prioritize national data, while cross-country comparisons may use a harmonized international dataset.
Missing data
Missing figures are not inferred from neighboring countries or unrelated periods. Interpolation should be used only when the method is clearly stated and the result is identified as an estimate.
Data review dates
Country profiles distinguish between the page review date and the reference year of each indicator. The review date records when the source and presentation were checked. It does not change the year represented by the underlying data.
Reporting an issue
Questions about a source, definition or calculation can be sent to support@demographer.org. Include the page address, indicator, displayed value and supporting source when possible.