Many National Statistical blogs over the last 12 months have provided updates on new releases and insights from our range of population statistics. The latest 2022-based national population projections benefit from a wide range of data to provide new projections that paint a picture of the potential future population of the UK. And, as James Robards explains, they are not forecasts. They take into account current and past trends, and as those patterns change, we adjust our projections accordingly.
It has been 12 months since our last population projections release but many of the demographic trends we were seeing a year ago have continued to change and new data has become available. This includes rebased statistics from the 2022 Census in Scotland and the more recent release of international migration estimates in November 2024.
Population projections are only as good as the data and assumptions it is possible to feed in. Their real value lies in giving people a range of different scenarios to support the planning of services.
Since last January we have revisited all possible data sources and assumptions about future levels of fertility, migration and mortality. Alongside this we have engaged with topic experts to benefit from their views on what the future may look like and their interpretation of the latest trends in the data. Today all of these insights and data sources culminate in the release of 2022-based national population projections (NPPs).
The latest projections
Overall, the UK population is projected to grow by almost 5 million over the next decade. The driver of this growth is migration, with natural change – the difference between births and deaths – projected to be around zero. These projections are based on current and past trends. They are not forecasts and don’t take into account what may or may not happen in the future. If trends in births, deaths and migration change, then so would our assumptions for use in future projections.
For instance, compared to our last projections which were 2021-based NPPs, we have decreased our assumptions for future fertility, increased our long-term assumptions for international migration and decreased our expectation of life expectancy improvement. The combined impact of these assumptions of future population change can be seen in the projections, especially in our most granular outputs by age and sex. For example, the number of younger people after the first 10 years is fewer than in the 2021-based because of the lower fertility assumption, while our projections of more people in the early 2030s aged 20 to 40 is reflective of the migration assumption being higher.
However, to some extent, the combined changes in our assumptions lead to many similarities with our 2021-based interim release, such as in the year in which the population is projected to reach 70 million, which remains mid-2026.
Our latest projections also highlight an increasingly ageing population, with the number of people aged over 85 projected to nearly double to 3.3m by 2047. This is, in part, because of the ageing of the baby boom generation, as well as general increases in life expectancy.
Variant projections
Variant projections are of importance for this release where we continue to see uncertainty and complexity in population change. Over recent years fertility has continued to fall to historically low levels, international migration has been at very high levels and mortality has continued to change after the Covid-19 pandemic and from the early 2010s, when we first started to see a slowdown in improvement in life expectancy. This all makes setting assumptions more challenging and uncertain than it has been in the past.
Today’s release includes a wide range of variant projections to enable users to see the potential implications of higher and lower drivers of population change. These give insights into what a single type of population change (e.g. lower mortality) and multiple trends (e.g. lower mortality, lower fertility and higher mortality) might mean for the future population. Feedback from users has been that they find the variant projections useful for a range of purposes – including informing policy decisions around education, for instance – and we have included comparisons between the range of variants.
Reviewing past projections
With each release of projections we try to be clear that these are not forecasts and that the future demographic pathway of the UK will inevitably differ to some degree from the projections. We know that looking back provides insights for us to consider in how we use population projections and the certainty we can place upon them. The ONS has a history of developing and publishing ‘accuracy reports’ to show how successive rounds of population projections have differed to population estimates, births, migration and deaths. Alongside the NPP release we have published ‘Comparing national population projections to estimates report’ which looks back to 1971 and shows how projections releases have differed to the eventual mid-year estimates and other components of population change.
Innovation for users
We’ve continued to innovate how we enable users to interact with and understand our data. For this release we have developed an interactive NPP Explorer tool where users and those interested in population change can set their own assumptions, see what the potential implications could be for the population and download the data. This also enables comparison to our accredited official statistics including variant projections.
In future releases we hope to provide more tools of this type to enable users to explore the data and use our underlying systems to get their own, bespoke, insights.
Subnational projections next
We will now accelerate our work towards the release of the 2022-based subnational population projections (SNPPs) for England. This is planned for release on May 9, reflecting the need for us to include NPP data within the SNPPs and the need for detailed review of the projections after they have been produced. Through 2024 we worked on many areas of the SNPPs in response to feedback we achieved through the engagement launched last January. We hope these new set of subnational projections will provide many more insights and meet as many uses as possible.
Join us to hear more about the projections
In our upcoming webinar ‘National Population Projections’ we’ll be explaining more of what has gone into the projections and some of the insights from the release. Mark your calendars for Monday 3 February 2025, from 1:30pm to 2:30pm and sign up via Eventbrite to secure your spot.
Need More Info?
For more details about this event and The Population in numbers – what’s changing? series, visit the ONS website or drop us an email at pop.info@ons.gov.uk.
Don’t miss out—sign up today.
James Robards is Head of Population and Household Projections