The constituencies for next year’s Senedd election have been confirmed.
Voters in each of the 16 new constituencies will elect 6 members via the closed list proportional representation system. The changes are part of wider reforms to the Senedd introduced by the Senedd Cymru (Members and Elections) Act 2024.
This article includes maps of the new constituencies, explains how they were chosen and looks ahead to what happens next.
Who decides the boundaries?
As required by the Act, the new constituency boundaries were decided by the Democracy and Boundary Commission Cymru, an independent Welsh Government-sponsored body.
In its review, the Commission was tasked with pairing the 32 UK Parliament constituencies into 16 Senedd constituencies.
When making its proposals, the Commission could take into account:
- Existing local government boundaries;
- “Special geographical considerations”, such as the size, shape and accessibility of a proposed constituency; and
- Local ties (including those connected to the use of the Welsh language) that would be broken by any proposals.
The Commission was required to give constituencies a single name to use in both Welsh and English, unless it considered that to do so would be unacceptable.
The Commission commenced its review in July 2024.
In September 2024, it published (and consulted on) its initial proposals. These were followed by revised proposals in December 2024. The revised proposals made two changes to the constituency pairings in Cardiff.
The Commission published its final report on 11 March 2025. In its final report, the Commission reversed its earlier change to the constituency pairings in Cardiff. It also confirmed that each constituency will have a single Welsh name.
Find your new Senedd constituency
Senedd Constituencies 2026 (PDF)
What happens next?
The Commission has submitted its report to the Welsh Ministers, and it has been laid before the Senedd. The Welsh Government is required to make secondary legislation to bring the Commission’s decisions into law.
The new constituencies do not require the Senedd’s approval, and will be adopted automatically.
While these constituencies will be in place for the Senedd election in 2026, there will be another review before the 2030 election. This will be a full review of the boundaries, with no requirement to stick to pairs of Westminster constituencies. The Commission has to report on this review by 1 December 2028.
Article by Josh Hayman, Adam Cooke, Sam Jones and Helen Jones, Senedd Research, Welsh Parliament
