(December 2014) Policymakers rely on population projections to assess future demand for resources and services. These projections, though based on research and expert opinions, are not certain.

Use these PRB publications, graphics, and video to learn more about how demographers analyze data on fertility, mortality, and migration to create population projections, and how assumptions can produce different results over time.


Infographic: Population Projections ›
This interactive infographic uses three main projections produced by the UN Population Division to illustrate how assumptions can produce significantly different results over time.

Understanding Population Projections ›
This PRB policy brief brief helps improve our understanding of population projections by highlighting some of the key assumptions on which they are based. The brief examines and discusses the population projections produced by the UN Population Division as an example.

As Fertility Changes, So Do Population Projections (launches in a pop-up) ›
Use PRB’s interactive Tableau graphics to compare population projections by country.

World Population by the Billion ›
World population is around 7 billion. How long did it take for the world to add each billion? What improvements in health and science helped population growth? And how long do demographers think it will take to reach 8 billion, and 9 billion?

The Decline in U.S. Fertility ›
This PRB fact sheet explains the recent decline in the U.S. fertility rate to 1.9 children per woman, a decline that represents the sixth straight year that the U.S. fertility rate has been below “replacement level” of 2.1 children per woman—the level needed for couples to replace themselves in the population.