Population Tool: How Will Global Populations Change in the 21st Century?

• Our World in Data has launched an interactive simulation tool for users to model how changes in fertility, life expectancy, and migration affect future population size and age structure.
• The tool is designed to provide insight into demographic uncertainty rather than replacing professional projections from entities like the United Nations.

Using the Simulation Tool

• Users can select a specific country and adjust three core variables for the years 2030, 2050, and 2100:
  • Fertility rates
  • Life expectancy
  • Net migration rates
• The interface provides immediate visual output showing how these customized assumptions alter total population numbers and the composition of age groups.

Purpose and Methodology

• The tool aims to help the public understand how demographic fluctuations impact national trends, such as the shrinking population observed in countries like South Korea.
• The model is intentionally simplified for browser-based performance; detailed technical documentation and a walkthrough are available for those interested in the underlying methodology.
• This project is part of a broader suite of demographic resources, including an explorer for historical data and standard UN projection scenarios.