Total Fertility Rate (TFR)
Definition
The average number of children a woman would bear over her lifetime if current age-specific birth rates remained constant. A TFR of 2.1 is considered the "replacement rate" needed to maintain a stable population.
Why It Matters
Fertility rates drive long-term population growth or decline. Countries below replacement face aging populations, labor shortages, and pension pressure. Those well above replacement face rapid population growth and resource strain.
How It's Measured
Calculated by summing age-specific fertility rates (births per woman at each age from 15 to 49). Published by the World Bank, UN, and national statistics agencies.
Current Value
US TFR: approximately 1.66; World average: approximately 2.3
Related Ranking
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Frequently Asked Questions
The average number of children a woman would bear over her lifetime if current age-specific birth rates remained constant. A TFR of 2.1 is considered the "replacement rate" needed to maintain a stable population.
Fertility rates drive long-term population growth or decline. Countries below replacement face aging populations, labor shortages, and pension pressure. Those well above replacement face rapid population growth and resource strain.
Calculated by summing age-specific fertility rates (births per woman at each age from 15 to 49). Published by the World Bank, UN, and national statistics agencies.
this entity is one of the U.S. population demographics concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the the U.S. Census Bureau ACS and decennial files data behind every per-entity page on the site.
In the the U.S. Census Bureau ACS and decennial files data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.
Source: U.S. Census Bureau ACS, 2026.