Deaths are projected to outnumber births in the UK every year from 2026 and the population is expected to grow at a slower rate over the next few decades than previously reported, according to the Office for National Statistics (ONS).

About 1.7 million people are projected to join the population between 2024 and 2034, pushing the total up 2.5% from 69.3 million to 71 million, before it starts to decrease in the mid-2050s.

This is smaller than the increase included in ONS figures published last year, which projected a rise of 3 million over the same period and the population jumping 4.3% to a total of 72.2 million by 2034.

The projections have been revised downwards to reflect the recent sharp fall in net migration, as well as lower fertility rates in the future.

James Robards, ONS head of household and population projections, said: “Our latest projections indicate slower population growth than previously projected.

“This is mainly due to lower migration assumptions – reflective of the recent steep fall in net migration – and lower fertility assumptions. At the UK level, the population is projected to peak in the 2050s before decreasing.”

The projections are not forecasts nor predictions and are based on current and past trends.

UK population growth is projected to slow even further during the 2030s and 2040s, before peaking at 72.5 million in 2054 and then going into decline, dropping to 72.1 million by 2064 and 71.4 million in 2074.

Previous projections suggested the population would continue to grow until 2096.

Net migration, the difference between the number of people moving long-term to the country and the number leaving, is expected to be the only driver of population growth in the UK over the next few decades.

Net migration to the UK stood at an estimated 204,000 in the year to June 2025, down 69% from 649,000 in the previous 12 months.

An additional 2.2 million people are projected to be added to the population through net migration in the 10 years to 2034, while natural change will see 450,000 more deaths than births, resulting in the overall growth projection for this period of 1.7 million.

The ONS figures suggest the population will peak at different times in the four countries of the UK.

While England is projected to have a peak of 62.1 million people in 2056, the peak is likely to come much sooner elsewhere, arriving in 2035 in Wales (3.2 million), 2033 in Scotland (5.6 million) and 2031 in Northern Ireland (1.9 million).

The total projected growth in the UK population in the 25 years from 2024 to 2049 is 3.1 million, or an increase of 4.5%.

This is notably lower than the growth in the preceding 25 years, from 1999 to 2024, when the population grew by an estimated 10.6 million, or a rise of 18.1%.

The figures also reflect the ongoing shift in the age structure of the UK population.

The number of people of pensionable age is projected to rise from 12.4 million to 14.2 million by 2034, when it will account for one in five of the total population.

In contrast, children under the age of 16 will make up a smaller proportion of the population, down from 12.6 million (18.2% of the total) to 11 million (15.5%).

By the time the UK population is projected to peak in 2054, pensioners will account for 22% of the total and under-16s will make up 14.5%.

Maike Currie, vice-president of personal finance at financial institution PensionBee, said: “The UK’s demographic dividend is turning into a deepening demographic drag. For the pension system, this means fewer future workers supporting more retirees.

“With earlier figures showing a third of those leaving the UK are aged 16 to 34, the pension system faces a double hit: fewer contributors and more retirees, putting real strain on the state pension and long-term investment flows.”