Total fertility rate (TFR)
The average number of children a woman would have over her lifetime, if current birth rates held steady.
In short
TFR is a snapshot, not a prediction for any one woman. It's the standard way demographers compare how fast different populations are having children, independent of age structure.
How it's calculated
TFR adds up the birth rates for women in every five-year age group, from about 15 to 49, for a single year, then treats that as one woman's lifetime. The multiplication by 5 converts single-year rates into the five-year interval used in most demographic data.
TFR = sum of age-specific birth rates × 5
Typical values
Why it matters here
When you compare two countries on the canvas, differences in TFR are usually the biggest reason one ridgeline keeps climbing while another flattens or turns down. It's the single number most responsible for the shape of a projection after 2023.
The global TFR fell from roughly 5.0 in 1950 to about 2.3 by 2023 — a transition that happened unevenly across regions. Sub-Saharan Africa still averages around 4.5, while East Asia and Southern Europe are well below 1.5. That gap is the main driver of divergent ridgeline shapes visible in the explorer today. Country-level TFR series going back to 1950 are available from the UN World Population Prospects fertility tables.
TFR through history
Before the demographic transition, most populations sustained a TFR of 5 to 7 just to offset high mortality. As sanitation improved and child survival rose, fertility began to fall — though not immediately. The lag between falling death rates and falling birth rates is the core mechanism behind the 20th-century population boom. Countries that completed the transition earliest, like France and Sweden, began their TFR decline in the 19th century; many lower-income countries are still mid-transition today. Our World in Data charts the long-run decline in fertility rates across all regions from pre-industrial levels to the present.
Frequently asked questions
What is a total fertility rate?
Total fertility rate (TFR) is the average number of children a woman would have over her lifetime if the age-specific birth rates of a given year held constant throughout her reproductive years, typically ages 15 to 49. It is the standard measure demographers use to compare childbearing levels across countries and time. Our World in Data publishes long-run TFR series for every country.
What TFR is needed for a population to replace itself?
In most high-income countries, a TFR of about 2.1 children per woman is needed for each generation to replace itself. The figure is slightly above 2.0 to account for childhood mortality and a natural sex ratio at birth slightly above 1:1. In higher-mortality settings, replacement-level TFR can be somewhat higher.
How does TFR differ from birth rate?
The crude birth rate counts births per 1,000 people and is strongly affected by age structure — a young population has more births even if each woman has fewer children. TFR removes that age-structure effect by using age-specific rates, making it a purer measure of fertility behaviour.
Why do some countries have a TFR below 1?
Several countries in East Asia and Southern Europe have recorded TFRs below 1.5, and some below 1.2. Factors include delayed marriage, high cost of living, limited parental leave, and cultural shifts around family size. A TFR this low implies the population would halve within a few generations without immigration. The UN's population overview tracks these trends at country and regional level.