When will Tanzania overtake Japan in population?

Japan has been shrinking since its 2010 peak, and the projection takes it from 124 million in 2024 to 105 million by 2050 on 1.2 births per woman. Tanzania, with 4.5 births per woman and a median age of 17, roughly doubles over the same period. In 1990 Japan had about 4.8 times Tanzania's population; the gap closes in the mid 2040s.

Tanzania is projected to overtake Japan in total population around 2044. At the crossover, both countries sit at roughly 111 million people. Today Japan is still larger, but the trend lines are converging and the order is set to flip within a generation.

The reason is a tale of two trajectories. Tanzania is on course to more than double over the century, moving from about 67.6 million in 2024 toward 262 million by 2100. Japan, by contrast, is projected to fall sharply, going from roughly 124 million to 77.0 million over the same period. Differences in fertility and age structure (Tanzania's median age near 17 versus Japan's near 49 today) explain much of the divergence.

Crossovers like this one are how the global population ranking is quietly rewritten. As faster-growing populations climb the table and slower-growing or shrinking ones slip down, the list of the world's largest countries in 2100 will look markedly different from today's. The 2044 crossing is one of the clearer signals of that shift.

As with all long-range projections, the exact year carries uncertainty. Under the UN's high and low fertility scenarios the crossover could arrive earlier or later, and the figures here follow the medium variant. Still, the direction of travel, Tanzania rising relative to Japan, is robust across the plausible range of outcomes.