United Kingdom Population

Population growth in the United Kingdom is now driven almost entirely by immigration, as the domestic birth rate has settled below the replacement level. Net migration has become one of the most contested issues in British politics, precisely because it is the main lever on the country's demographic future. Beneath the headline numbers lies the same quiet ageing seen across wealthy Europe.

United Kingdom is home to about 69.7 million people in 2026, the 22nd largest population of any country. A country of Northern Europe, its trajectory to 2100 is governed by how births, deaths and migration play out. It packs in roughly 288 people per square kilometre.

United Kingdom is projected to keep growing until about 2073, when its population peaks at roughly 76.1 million before a gradual decline sets in, leaving it near 74.4 million by 2100. It passed the 50 million mark around 1951.

With fertility near 1.55, just under the 2.1 replacement mark, natural increase is fading. Net inward migration adds to the population each year and partly offsets the low birth rate.

The median age is set to climb from about 40 today to roughly 48 by 2100, while life expectancy, near 81 years, keeps rising. A rising median age means fewer working-age people supporting each retiree over time.

Read these numbers as the midpoint of a range. Under the UN's high and low fertility paths United Kingdom's 2100 population could land well above or below the figures here; the medium variant is simply the central case.