National population projections: 2021-based interim

• Over the 15 years between mid-2021 and mid-2036, the UK population is projected to grow by 6.6 million people (9.9%) from an estimated 67.0 million to 73.7 million; this includes 541,000 more births than deaths, and net international migration of 6.1 million people. 

• The UK population is projected to reach 70 million by mid-2026; this growth is faster than in the 2020-based projections released in January 2023 with the projected increase mainly resulting from international migration. 

• The population projections for the UK are based on an assumption of long-term net international migration of 315,000 per year from year ending mid-2028 onwards; this is based on expert views and the latest data covering the last 10 years; note migration assumptions do not directly account for recent and future policy or economic changes and there is always some uncertainty in estimates of migration, meaning actual levels of future migration and resulting population may be higher or lower than those assumed in these projections. 

• There will be an increasing number of older people; over the next 15 years the size of the UK population aged 85 years and over is projected to increase from 1.6 million (2.5% of the total population) to 2.6 million (3.5%).

These projections use the latest provisional estimates of international migration to year ending June 2023, which will be revised as more data become available. See Section 4: Measuring the data for more information.

Users requiring national population projections for Scotland should continue to use the 2020-based interim national population projections: estimated international migration variant. No 2021-based projections have been published for Scotland because reconciliation and rebasing of population statistics, including international migration statistics for 2012 to 2022 incorporating insights from Scotland's Census 2022, are yet to be finalised. These data will be available and incorporated into the 2022-based projections, which are planned for release in October to November 2024.

The assumptions of future fertility and mortality are reused from our 2020-based NPPs. All assumptions will be updated in the next release, provisionally announced for publication in late 2024 on the ONS release calendar.

The UK population, which was estimated to be 67.0 million in mid-2021, is projected to rise by 6.6 million to 73.7 million over the next 15 years to mid-2036 (a 9.9% increase). In comparison, between mid-2006 and mid-2021 the population is estimated to have grown by 6.2 million (a 10.2% increase).

The total projected increase in the UK population over the next 25 years is proportionately less than that over the past 25 years (Figure 1). Between mid-1996 and mid-2021, the population grew by 8.9 million (15.3%); between mid-2021 and mid-2046, it is projected to grow by 9.5 million (14.2%).

Focusing on the 15 years between mid-2021 and mid-2036, the total projected growth for the UK population is 6.6 million (9.9%). During this period between mid-2021 and mid-2036, the projections for the UK as a whole suggest:

• 10.8 million people will be born

• 10.3 million people will die

• 13.7 million people will immigrate long term to the UK

• 7.6 million people will emigrate long term from the UK

This means that of the projected 6.6 million increase in the total population, 0.5 million (8.2% of the total projected increase) is projected to result from the higher number of births than deaths, and 6.1 million (91.8% of the total projected increase) is projected to result from net international migration.

By mid-2035 it is projected that there will be more deaths (736,000) than births (734,000). Natural change is the difference between the number of live births and deaths. Over the 15 years between mid-2021 and mid-2036, natural change is projected to be 541,000.

Table 1 contains details of the long-term assumptions for fertility, mortality and international net migration (the difference calculated between immigration and emigration). These assumptions should not be interpreted as predictions of the future, but as plausible scenarios based on what has happened in the past.

National population projections table of contents

You can use our table of contents tools to navigate through this release. This tool contains links to the full range of data and documentation for this release and past releases in the same series. It lists all the datasets available and allows you to filter by geography. You can also access methodology information and all related background information associated with this national population projections release.

National population projections (NPPs) provide an indication of the potential future population size of the UK and its constituent countries. These statistics are widely used in planning, for example: economic and fiscal forecasts, health, education and pensions. The Office for National Statistics (ONS) normally produces NPPs for the UK and its constituent countries every two years, although this has changed around the time of the census and in response to user needs. The most recent NPPs before this release were 2020-based, published in January 2023 and followed an earlier release in January 2022.

These projections have been produced to help users ahead of Spring Budget 2024 by providing NPPs using the latest data along with evidence and expert views on potential future international migration. The use of the term "interim" in the release title is to reflect that these projections reuse mortality and fertility assumptions from the previous 2020-based NPPs, do not include the range of variant projections that are usually published and are being published as a headline-only release ahead of 2022-based NPPs.

The mid-year population estimate for mid-2021 is used as the start point of the projection; this is the base population which uses census data for England, Wales and Northern Ireland and rolled-on mid-year estimates for Scotland.

This release provides a principal national population projection and a variant zero net migration projection. There will be no high and low international migration projection variants as this is an interim release. We advise users to use these national population projections instead of the 2020-based interim national population projections: year ending June 2022 estimated international migration variant published in January 2023.

This release includes new international migration assumptions, which have been developed using the latest migration data available published in our Long-term international migration, provisional: year ending June 2023. It also provides revised estimates for UK international migration for mid-2012 to mid-2023. International migration estimates for mid-2022 to mid-2023 are provisional and will be updated when more complete data are available.

Expert advice was sought at a panel meeting on 12 December 2023 in developing new international migration assumptions where experts were asked for their views on prospects for international migration over both the short-term (the next five years) and long-term (the next 25 years). The expert views and the latest data pointed towards an expectation of higher international migration than the assumptions used in our 2020-based interim NPP assumptions of January 2023.

From reviewing expert advisory feedback and our own research, the National Population Projections Committee (NPP) comprising the Office for National Statistics (ONS), National Records of Scotland (NRS), Northern Ireland Statistics and Research Agency (NISRA) and the Welsh Government agreed to base the long-term assumptions on an average of 10 years of historical international migration data including the years ending mid-2022 and mid-2023. This has a long-term average in the ranges provided by our expert advisory feedback and leads to a long-term assumption of 315,000 net migration from the year ending mid-2028. This long-term assumption is an increase from our previous assumption of 245,000 net migration used in our release 2020-based interim national population projections: year ending June 2022 estimated international migration variant.

The short-term assumptions are calculated by use of a five-year interpolation from the latest provisional estimate for mid-2023 to reach the long-term assumption in mid-2028. Please see the table of contents for a dataset providing the underlying international migration estimates which have informed the assumptions, and the assumptions for each year and country.

There is uncertainty over future directions and levels of international migration. Over recent years there have been marked changes in international migration arising from free movement ending for EU nationals as part of the introduction of the new immigration system in January 2021, the easing of travel restrictions following the coronavirus (COVID-19) pandemic in July 2021, and external developments such as the war in Ukraine. Potential future changes in international migration are not directly accounted for in the migration assumptions used in these projections.

To show what levels of net international migration could look like in future if it was higher or lower, Figure 2 shows what high and low migration variants might look like if the long-term assumption for international migration was 20% higher or lower than the principal assumption (315,000 net migration). For more information on the development, use and interpretation of variant projections see our Variant national population projections for the UK and subnational population projections and household projections for England: user guide.

We agree demographic assumptions with the Northern Ireland Statistics and Research Agency (NISRA), the National Records of Scotland (NRS) and the Welsh Government. Assumptions for cross-border migration (migration between UK constituent countries), fertility and mortality have been reused from the National population projections: 2020-based interim and our data-only release, 2020-based interim national population projections: year ending June 2022 estimated international migration variant. Information on the data, methods and assumption-setting process used to produce the 2020-based interim NPPs can be found in our Fertility assumptions article and Mortality assumptions article.

Age and sex distributions for international migrants used in this release are different for each country because of data availability:

• England and Wales: mid-2018 to mid-2022

• Northern Ireland: mid-2018 to mid-2022

• Scotland: mid-2017 to mid-2021 

Further information on data sources used to produce the 2020-based interim national population projections can be found in our Background, methodology and assumption setting article.

Quality and methodology information for NPPs, detailing the strengths and limitations of the data, methods used and data users can be found in our Quality and Methodology Information (QMI).