Overview of electoral systems used for the UK's four legislatures

A table overview of the electoral systems in the UK including the number of seats, voting age, constituency structure and frequency of elections.

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Source: Institute for Government analysis of House of Commons Library, 'Voting Systems in the UK', July 2025.Notes: Prior to the 7 May 2026 election, the Senedd used the additional member system (AMS) to elect 20 regional Members and 40 constituency Members.Get the dataEmbed Download image