Sub-Saharan Africa: the world's population growth engine through 2100
While most of the world's population growth story is one of slowing and eventual decline, sub-Saharan Africa follows a different trajectory. With average fertility still around 4.5 children per woman and a population that is among the youngest on Earth, the region will account for more than half of all global population growth between now and 2100.
The arithmetic of a young, high-fertility region
Sub-Saharan Africa's population growth is driven by the interaction of two forces: a still-high total fertility rate and a very young age structure that means the number of women entering reproductive age each year is itself growing. This is natural increase compounded by population momentum — even if every woman in the region decided today to have exactly 2.1 children, the population would keep growing for another 50–70 years simply because of the large cohorts already born.
The UN WPP 2024 projects sub-Saharan Africa's population growing from approximately 1.2 billion today to between 3.0 and 3.8 billion by 2100, with the range reflecting uncertainty about how fast the fertility transition proceeds. The IHME's alternative model places the upper end lower, assuming faster fertility decline, but both agree on the direction.
Why fertility is still high — and why it's falling
High fertility in sub-Saharan Africa is not a single story. It reflects a range of factors that vary enormously by country, urban/rural split, educational attainment, and access to healthcare. In rural areas with limited access to contraception, high child mortality historically incentivised large families as an insurance strategy. DHS survey data consistently shows that unmet need for family planning remains high — typically 20–30% of married women of reproductive age in West and Central Africa.
But the transition is happening. Ethiopia's TFR fell from around 7.0 in 1990 to approximately 4.0 by 2023. Rwanda dropped from 8.3 in 1960 to around 3.8. Botswana is at 2.8. The countries driving these declines share common features: rising female secondary school enrolment, expanding community health worker networks, and stronger political commitment to family planning. The WHO family planning fact sheet outlines the evidence base for each intervention.
Nigeria: the continent's demographic anchor
Nigeria deserves special attention because its demographic trajectory matters more than any other single African country for global totals. With approximately 225 million people today and a TFR still around 5.1, Nigeria is the most consequential fertility outlier in the world. The UN projects Nigeria overtaking the United States as the third most populous country by the 2040s and potentially reaching 400–500 million by 2100.
Nigeria has not conducted a national census since 2006. Population estimates rely on DHS surveys and projection models, meaning actual current population could differ from estimates by tens of millions. The National Bureau of Statistics Nigeria conducted a new census in 2023 whose results remain under review.
The demographic dividend opportunity
The same young age structure that produces rapid population growth also creates a potential economic opportunity. As fertility falls, the share of the population in working age temporarily rises while both youth and old-age dependency are relatively low. East Asian economies — South Korea, Taiwan, Thailand — extracted enormous economic gains from this window in the late 20th century. Sub-Saharan Africa is positioned to enter this phase across different countries at different times over the next 30 years.
Whether the dividend materialises depends entirely on job creation keeping pace with workforce growth. The ILO Africa regional office estimates the continent needs to create roughly 20 million new jobs per year to absorb new labour market entrants — a scale with no precedent. Our World in Data's demographic dividend explainer contextualises the historical evidence.
Frequently asked questions
Why is sub-Saharan Africa's population growing so fast?
The region combines the world's highest remaining fertility — average TFR around 4.5 — with rapidly improving child survival from vaccines, nutrition, and malaria control. Falling mortality while fertility remains high is the classic demographic transition gap that drives rapid growth.
How much of future global growth will come from Africa?
Under the UN medium variant, sub-Saharan Africa accounts for more than half of all global population growth to 2100. Africa's total population is projected to reach 3.5–4 billion by 2100, depending on the pace of fertility decline.
Will Africa's fertility rate fall?
Yes — it is already falling. Ethiopia and Rwanda have seen significant declines. Unmet need for family planning, tracked by DHS surveys, remains a key driver of remaining high fertility in West and Central Africa.