8 Billion and Growing: World Population Milestones Throughout History

We will become a world of 8 billion in 2022. After passing the 7 billion milestone in 2010, it has only taken 12 years to add the latest billion.

When Did the World Population Reach 1 Billion?

Until the Industrial Revolution began, birth rates and death rates were both very high, which kept the global human population relatively stable. In fact, it took all of human history, until around 1804, to reach 1 billion people. Modern medicine and sanitation played heavily in reducing mortality rates—especially among infants and children—but there wasn’t yet a reliable way to reduce fertility (the first modern contraceptive, the birth control pill, wasn’t introduced until 1960). The drop in mortality while fertility remained unchanged caused the beginning of what is now known as the J-curve (see below). With more people surviving to adulthood and then having kids of their own, the human population started growing exponentially.

When Did the World Population Reach Other Milestones?

It took 123 years to reach 2 billion, and only 33 years to reach 3 billion. The last several billion milestones (4, 5, 6, 7, and 8 billion) were reached in 14, 13, 11, 12, and 12 years, respectively. The UN projects that it will take 15 years to reach the 9 billion mark and 21 more years to reach 10 billion.

Most of the growth around the world occurs in less developed countries—places already struggling to provide for their citizens, especially in the midst of the climate crisis (which has been disproportionately caused by people in high-income countries). In fact, 96% of global population growth since the 7 billion milestone has occurred in less developed countries.

World Population Growth Graph

The growth of the human population over time can be depicted by what is known as the population j-curve, which shows how sharply our population has risen in the last 200+ years.

The steep ascent over the past two centuries has created growing pains for families, communities, countries, and the planet. Consumption levels vary by individual and by world region, but everyone has infrastructure needs and contributes to environmental degradation to some degree. The more people who need food, water, shelter, health care, education, and employment, the more our agricultural systems, human institutions, and public infrastructure will need to grow and the more the environment and other species feel the strain.

When Will the Population Reach 9 Billion?

The United Nations Population Division projects that the world will reach 9 billion people in 2037 and 10 billion in 2058. Without increased investment in voluntary international family planning programs and other initiatives that correlate with lower fertility (child survival, girls’ education, women’s empowerment, formal sector employment, etc.), we could be looking at a situation where the next couple milestones are crossed earlier than currently projected.

This post was originally written in June 2021. It was updated in July 2022 after the United Nations Population Division released its World Population Prospects 2022 data and publications.