The UK population is projected to exceed 70 million by mid-2031, according to the Office for National Statistics.
In the next decade, the population is expected to increase by 3 million, from an estimated 66.4 million in mid-2018 to 69.4 million in mid-2028.
England’s population is projected to grow 5% in the next decade, a faster rate than Northern Ireland (3.7%), Scotland (1.8%) and Wales (0.6%).
During the next 10 years, the projections for the UK as a whole suggest 7.2 million people will be born, 6.4 million people will die, 5.4 million people will migrate long-term to the UK, and 3.3 million people will emigrate long-term from the UK.
Net international migration is expected to account for 73% of the UK population growth over the next decade, while more births than deaths could account for 27%.
Overall, the UK’s population growth rate is slower than in projections made in 2016, with the expected population anticipated to be 400,000 less in mid-2028 and 900,000 less in mid-2043.
The pace of growth is expected to slow based on assumptions that fewer children will be born, in light of recent falls in fertility rates, and a slower rate of increase in life expectancy.
The proportion of people aged 85 years and over is projected to almost double during the next 25 years.
The projected population growth is less than that over the past 25 years. Between mid-1993 and mid-2018, the population increased by 9 million (15.1%), but between mid-2018 and mid-2043, it is projected to grow by 6 million (9%).
Anna Dixon, the chief executive at the Centre for Ageing Better, said the figures showed the age of the population was “dramatically shifting”.
She added: “These longer lives are a huge opportunity but big changes are needed to our workplaces, homes, health services and communities if we are to ensure everyone is able to age well.
“We also need to rethink our attitudes to age and tackle the ageist attitudes which hold back too many people from enjoying a good later life.”
Andrew Nash, who works in the population projections unit at the Office for National Statistics, said: “The UK population is projected to grow by 3 million people by 2028. This assumes migration will have a greater impact on the size of the population than the combination of births and deaths.
“Although migration declines at first and the number of births is stable, the number of deaths is projected to grow as those born in the baby boom after world war two reach older ages.
“The population is increasingly ageing and this trend will continue. However, because of the expected rise in the state pension age to 67, it is projected that slightly fewer than one in five people will be of pensionable age in 2028, a similar proportion to today.”