The Office for National Statistics said the UK’s population is now expected to reach 71.0 million by mid-2034, down from a previous projection of 72.2 million, after it reduced its assumptions about future immigration.
The ONS estimates the population will grow from about 69.3 million in mid-2024 mainly because net migration will add roughly 2.2 million people over the decade, while natural change — deaths exceeding births — will shrink the population by about 450,000. Net migration is projected to be the only source of population growth over the period.
The lower outlook could add to fiscal pressures for Chancellor Rachel Reeves ahead of the autumn budget, the agency said. It also stressed that these figures are not forecasts but are extrapolations of recent trends and do not attempt to predict future policy shifts or other drivers of migration, fertility or mortality.
The projection highlights an ageing population: the number of pensioners is expected to rise about 15% to 14.2 million between 2024 and 2034, while the population of children under 16 is forecast to fall by around 13%.
The ONS trimmed its fertility assumption to 1.42 children per woman from 1.45 in the previous projections. It made a larger reduction to its assumed annual net migration rate — to 230,000 from 340,000 in last year’s report — reflecting the sharp fall in net migration since its 2023 peak and guidance from experts.
Net migration surged after the COVID-19 pandemic, driven by pent-up demand and changes under the government of then-prime minister Boris Johnson that relaxed some rules for low-paid care workers and their families. After approaching 1 million in the year to June 2023, net migration fell to 204,000 in the year to June 2025.
Regionally, England is expected to grow faster than the rest of the UK, with population rises of about 2.9% by mid-2034 compared with 1.0% in Wales, 0.6% in Northern Ireland and 0.3% in Scotland.
