Skip to main content

2020-based interim national population projections

On 12 January, the Office for National Statistics (ONS) published interim 2020-based national population projections for Wales and the countries of the UK.

Population projections are subject to uncertainty and are based on assumptions on future trends in fertility, mortality and migration. The impacts of the coronavirus (COVID-19) pandemic on demographic behaviour is not yet clear and this contributes to greater uncertainty. Further information is available in the Office for National Statistics bulletin and methodology documents (ONS).

The Office for National Statistics (ONS) has published a notice to inform users of an error affecting international migration out of Wales. The ONS states that the impact of this on the projections for Wales is modest, with the population projected to be around 2,700 lower by 2030 than what is published, and around 16,400 lower by 2045. In consultation with the Welsh Government, the ONS has decided not to replace the product. For further information, please visit the ONS website.

Main points

  • Between mid-2020 and mid-2030, the population of Wales is projected to increase by 2.6%, from 3.17 million to 3.25 million.
  • Between mid-2020 and mid-2045, the population of Wales is projected to increase by 4.2%, from 3.17 million to 3.30 million.
  • The population of the UK is projected to increase by 3.2% between mid-2020 and mid-2030, to 69.2 million, with the population projected to grow in each of the four countries.

A headline summarising the Welsh data has been published, alongside the data on StatsWales.

2021 Census

Following the recent ONS consultation on 2021 Census outputs, they have published a full list of proposed changes to the phase one proposals (ONS), based on respondent feedback. They are currently evaluating responses about the later phases of their release schedule. They will address these in part two of their consultation response, which they will publish in early 2022.

In the latest blog about Building the richest picture of our population (ONS), the ONS confirmed that they are aiming to publish the first release of population and household estimates for Wales (and England) in late May. They will confirm the exact date once they have completed their processing and quality assurance. Proposed outputs and analysis release plans are available on the ONS website.

Local authorities have been invited to help in the quality assurance of provisional census estimates for the first time, scheduled to take place in February and March. Further information about the ONS’ plans is available. All local authorities in Wales are encouraged to be involved in this process.

Records from the 1921 Census in Wales (and England) were released on 6 January, just over 100 years after the census was held. Further information can be found on the National Archives website.

Update on uncertainty in population estimates

On 28 January, the ONS published an update to its measures of uncertainty in population estimates data (ONS), which details some methodological changes and includes uncertainty data for 2020. More information on the methodology can be found in the previous release (ONS).

For Wales, the 95% uncertainty interval for the population estimate in 2020 was +/- 3% from the central value, with three local authorities having intervals of over +/- 5%. For 7 out of the 22 local authorities in Wales, the 2020 population estimate was outside of the calculated uncertainty interval.

Update on population statistics transformation

On 28 January, the ONS published an update on its plans for population estimates and projections. A blog (ONS) was published alongside this discussing how the ONS will deliver richer and more timely insights on the population.

Population estimates by ethnic group and religion

On 16 December 2021, the ONS published experimental statistics (ONS) on the population of England and Wales by ethnic group and religion (ONS).

Please see the Social justice and equality section of the statistics wales quarterly update for more information.

Migration and European Union Settlement Scheme statistics

StatsWales user engagement

The Welsh Government is planning to carry out research on how people use our open data platform StatsWales. We’re keen to gather views from a wide range of users, including from people working for public bodies, the third sector and beyond. The user research may be carried out by a contractor and the results will shape the future direction of the StatsWales site. If you use StatsWales and would like to take part in this research please get in touch.

Welsh language statistics

For information on Welsh language statistics, please see the Statistics Wales quarterly update.


Martin Parry

Telephone: 0300 025 0373



Telephone: 0300 025 8099