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Analysis of the rebased mid-year population estimates (2012 to 2021) following Census 2021, Wales

On 9 April, the Welsh Government published an analysis of the rebased mid-year population estimates (mid-2012 to mid-2021) following Census 2021, for Wales.

This statistical article provides analysis of the Office for National Statistics (ONS) rebasing of mid-year population estimates following Census 2021 for Wales and England. The article focusses on the rebased estimates for Wales and local authorities in Wales for the period mid-2012 to mid-2021.

Main points

  • The rebased population estimates decreased the population of Wales by 66,600 between mid-2011 and mid-2021, from 3.17 million to 3.11 million.
  • This is a decrease of 2.1%, which is a proportionally larger decrease than that seen for England (decrease of 0.4%) during the same period. 
  • The rebased population estimates were lower than the rolled-forward population estimates for 20 of the 22 local authorities in Wales. 
  • Newport and Wrexham were the only local authorities whose rebased population estimates were higher than the rolled-forward estimates.
  • The largest negative difference between the rolled-forward and rebased population estimates was in Gwynedd, whose population was decreased by 6.2% between mid-2011 and mid-2021, from 124,800 to 117,100.
  • During this period the majority (58,700) of the overall decrease in Wales’s population as a result of the rebasing exercise, was made up of unattributable population change - change that could not be certainly accounted for by changes to births, deaths, or migration.

The rebased population estimates can be found on StatsWales, while the rolled forward estimates can be downloaded here.

If you have any questions, please contact us on

Electoral registration statistics

On 11 April, the ONS published electoral statistics on the number of electors as at 1 December 2023. They have been published as data tables only.

The local government electors data for Wales, published by the ONS, do not reflect the changes to eligibility criteria for Senedd and local government elections in Wales since 2020 for all constituencies in Wales. The information that is collected by the ONS from electoral registration officers in Wales does not currently include all 16 year old electors and 15 year old attainers in Wales registered to vote in the Senedd and local government elections in all constituencies. We continue to work with the ONS to resolve this matter so that we can publish corrected statistics for Senedd and local government electors in Wales for the period 2020 to 2023. Please note, this also means we are unable to update our StatsWales tables. See the ONS data tables for more information.

We published a headline summarising the data for UK parliamentary electors in Wales.

Main points

  • The total number of UK parliamentary electors registered to vote as at 1 December 2023 in Wales was 2,304,800.
  • This is similar to 1 December 2022, when 2,304,700 electors were registered to vote.
  • The total number of UK parliamentary electors registered to vote in the UK as a whole increased by 0.3% between 1 December 2022 and 1 December 2023.

Please note that for some constituencies in Wales (and in England), the ONS has had to use electoral registration data from 2022 as an estimate of electoral registrations for 2023. More information can be found in our headline.

If you have any questions, please contact us on

National Park estimates

On 3 May, the ONS released mid-2021 and mid-2022 national park population estimates for Wales and England. These have just been published as data tables.

We aim to update our National Park StatsWales tables as soon as possible. 

If you have any queries about the data, please contact us at

UK long-term international migration, provisional: year ending December 2023

Welsh language statistics

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

Contact details

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