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Data Provider: Welsh Government National Statistics Population projection components of change by local authority and year
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[Collapse]Population at end of year3,146,1573,154,0913,162,1173,170,0563,177,9673,185,8293,193,6093,201,2653,208,7013,215,8443,222,6703,229,2973,235,9133,242,3433,248,5583,254,6193,260,6603,266,6713,272,6263,278,4373,284,2953,290,3123,296,4653,302,7203,309,154
Population at end of year[Expand]Population at start of period3,138,6313,146,1573,154,0913,162,1173,170,0563,177,9673,185,8293,193,6093,201,2653,208,7013,215,8443,222,6703,229,2973,235,9133,242,3433,248,5583,254,6193,260,6603,266,6713,272,6263,278,4373,284,2953,290,3123,296,4653,302,720
[Expand]Net UK migrants3,7974,4904,9845,3655,7286,0046,2636,4916,6406,7336,7486,8347,0817,0937,0447,0407,1347,1487,0976,9506,9377,0377,1467,2507,371
[Collapse]Net overseas migrants6,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,6536,653
Net overseas migrantsInward overseas migrants16,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,28116,281
Outward overseas migrants9,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,6289,628
[Expand]Total fertility rate1.
[Expand]Standardised mortality ratio105.8106.9105.8104.8103.8102.8101.8100.899.999.
[Expand]Expectation of life at birth80.079.980.
[Expand]Special population - prisoners3,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,0703,070


General description

This dataset provides the components of change involved in the calculation of the population projections for local authorities in Wales. Data cover the change between each successive projection year and relate to the change from the middle of each year to the middle of the following year. The first year's data represent the change from the base year of mid-2018 to mid-2019, through the projection period to show the change for mid-2042 to mid-2043. This is the fifth set of population projections published for the 22 local authorities in Wales.

Note that the projections become increasingly uncertain the further we try to look into the future.

Data collection and calculation

Population projections provide estimates of the size of the future population, and are based on assumptions about births, deaths and migration. The assumptions are based on past trends. Projections only indicate what may happen should the recent trends continue. Projections done in this way do not make allowances for the effects of local or central government policies on future population levels, distribution and change.

The 2018 population estimates have been used as the base for the local authority projections. The projected population is for 30 June each year. The base population estimates are based on the usually resident population. Usual residents away from home temporarily are included, but visitors are excluded. Students are counted at their term-time address. It should also be noted that the UN definition of an international migrant is used - those changing country of residence for a period of at least 12 months. Short-term migrants (e.g. migrant workers from Eastern European countries) are not counted in the population estimates and hence are not included in the population projections. The projections are based on an assumed pattern of migration based on projecting forward the average migration patterns over the last five years.

The Chief Statistician published an update in February 2020, giving an overview of the methodological changes that had been made to the local authority projections since the 2014-based local authority projections. This included:
• changing the assumptions for internal migration, so that they were based on migration rates rather than fixed numbers
• constraining the sum of the local authority population projections, and some of the component parts, for the 22 local authorities in Wales to the 2018-based national population projections published by the ONS
Another update was issued in July 2020, announcing the publication date for the revised local authority population and household projections, and the decision to revert to not constraining the local authority population projections.
Following discussions with the Wales Subnational Projections (WaSP) group, we made the decision to revert, in part, to the previous methodology for calculating local authority population projections by removing the constraining to the national population projections. The decision to constrain to the national population projections initially was made as a result of the incorrect national population projections showing a different trend to the local authority population projections. However, as this is no longer the case, we have reverted to the original methodology of not constraining in order to provide better continuity with previous local authority population projections, so that they are mainly driven by local trends for births, deaths and migration.
We have, however, retained the change made to the assumptions for internal migration so that they continue to be based on migration rates rather than fixed numbers. Further information can be found in the update.

We will continue to refine this methodology prior to our next set of subnational projections and take account of user feedback.

Two variants are also published covering two different scenarios, a high population variant and a low population variant.

Frequency of publication

Every two to four years

Data reference periods

Data are published for the period 2018 to 2043.

Users, uses and context

See the local authority population projection statistical release in weblinks.

Rounding applied

Data are rounded independently to the nearest whole number and may not add exactly.

Revisions information

These data replaced the 2014 local authority population projections for Wales as the formal estimates of population growth.

On Monday 18 May 2020, the ONS issued a notice on its website informing users that they had identified an error affecting the 2018-based national population projections. The error was caused by incorrect processing of cross-border flows between Wales and England, resulting in the projected mid-2028 population for Wales being approximately 65,000 too low, and that for England being approximately 65,000 too high.
Having consulted with our expert group about the implications for our statistical products that were based on the 2018-based national population projections, we decided to withdraw the 2018-based local authority population projections and household projections.
The ONS published corrected national projections for Wales on Thursday 11 June. These local authority projections are based on the corrected 2018-based national population projections for Wales. Further information about the corrections can be found in the 2018-based local authority population projections release, as well as an analysis of how these corrected projections compare with the previously published projections.


Population projection components of change by local authority and year, 2018 to 2043

Last update

March 2020 March 2020

Next update

No longer updated. This will be replaced by a future projection.

Publishing organisation

Welsh Government

Source 1

2018-based projections for local authorities in Wales, Welsh Government

Contact email


National Statistics

Lowest level of geographical disaggregation

Local authorities

Geographical coverage

Local authorities

Languages covered

English and Welsh

Data licensing

You may use and re-use this data free of charge in any format or medium, under the terms of the Open Government License - see

Statistical quality

See the local authority population projection statistical release in weblinks.


Population projections; population growth; migration; natural change; births; deaths