Projection (medium variant)
The UN's central estimate of future population, one of several scenarios it publishes.
In short
The medium variant is the UN's single best guess, not the only future it publishes. Low and high variants exist too, mostly differing in how fast fertility is assumed to change.
How it's built
Starting from the latest estimate, the UN projects each country forward using assumptions about fertility, mortality and migration. The medium variant uses its central assumption for each; the low and high variants substitute a lower or higher fertility path, holding most other assumptions the same.
Note This site currently shows only the medium variant. Low and high variants exist in the UN's published data but aren't part of this canvas today.
The three most common variants
Why it matters here
Every ridgeline after 2023 on the canvas is the medium variant, drawn with a hatch fill and a dashed edge. It's a reasonable single scenario, not a certainty — the further out a projection reaches, the more the three variants pull apart from each other.
By 2100 the spread between the UN's low and high variants is roughly 7 billion people — wider than the entire world population in the 1960s. Treating any single projection as a forecast beyond 30 to 40 years overstates what demographers can reliably know. The full probabilistic range of the UN's projections, including 80% and 95% confidence intervals, is visualised on the UN WPP probabilistic projections page.
Frequently asked questions
What is the medium variant projection?
The medium variant is the UN's central scenario for future population growth. It uses the UN's best central assumptions about how fertility, mortality, and migration will change. It is the most widely cited variant, though it represents one plausible path, not a guaranteed outcome. The full set of variants and their assumptions is published by the UN World Population Prospects.
How is the medium variant different from the low and high variants?
All three variants use the same assumptions about mortality and migration. What differs is the fertility path. The low variant assumes fertility settles about half a child lower than the medium case; the high variant assumes about half a child higher. Over 80 years, this small difference compounds into billions of people — by 2100 the gap between low and high is roughly 7 billion. Our World in Data illustrates all three paths together in a single chart.
Is the medium variant a prediction?
Technically, it is a projection, not a prediction. A projection shows what happens under a specific stated set of assumptions. A prediction claims to know what will actually occur. The UN calls these scenarios. In practice many journalists and policymakers treat the medium variant as a best-guess forecast — which it broadly is — but uncertainty grows substantially beyond 20 to 30 years. Probabilistic population projections in Population and Development Review explains how uncertainty is formally quantified.
How does this site show projections?
Every ridgeline after 2023 on the canvas is the medium variant, drawn with a hatched fill and a dashed edge to distinguish it visually from historical estimates. Currently only the medium variant is shown — low and high variants exist in the UN's published data but are not yet part of this canvas.