Common Questions

What is the D'Hondt method?: A proportional representation seat allocation formula that divides each party's vote by successive integers (1, 2, 3...) and awards seats to whichever party has the highest quotient at each step.
How does D'Hondt work in the 2026 Senedd election?: Voters choose a party; seats in each of 16 constituencies (6 seats each) are allocated by D'Hondt using party vote totals. A party needs roughly 12% in a constituency to win any seat there.
What percentage of the vote do you need to win a Senedd seat in 2026?: Approximately 12% of the vote in a given constituency, according to Wales Governance Centre estimates. Below that threshold, a party wins nothing in that constituency regardless of national share.
Did Wales previously use D'Hondt?: Not for all seats. The old Additional Member System used D'Hondt for regional list seats only. The 2026 reform applies D'Hondt to all 96 seats across 16 unified constituencies.
How many Senedd seats are there in 2026?: 96 seats across 16 constituencies of 6 seats each, up from 60 seats in the outgoing chamber.

Background

The D'Hondt method is a highest-averages seat allocation system for proportional representation elections. A party's vote total is divided by 1, 2, 3, and so on; seats are awarded sequentially to whichever party has the highest resulting quotient at each step. The method slightly favours larger parties compared to other PR formulas (such as Sainte-Laguë) but remains far more proportional than first-past-the-post. It is used in the European Parliament, the Northern Ireland Assembly, the Scottish Parliament regional lists, and — from 2026 — the Senedd.

For the 2026 Senedd election the D'Hondt method applies across 16 constituencies, each returning 6 Members of the Senedd (MSs), for a total of 96 seats. Voters cast one vote for a party; individual candidates are selected by internal list order. The Wales Governance Centre and the Senedd Research Service estimate a party needs roughly 12 per cent of the constituency vote to win a single seat. That threshold matters: a party polling below 12 per cent in every constituency wins no seats regardless of national share. The method replaced the Additional Member System (AMS) used in the 1999-2021 Senedd elections and was legislated by the Senedd Reform Act 2024.

Without D'Hondt, the 7 May 2026 Senedd election would revert to first-past-the-post dynamics that historically crushed smaller parties in Wales. The formula is the direct mechanism through which Plaid Cymru's projected plurality and Reform UK's projected representation both become arithmetically possible — making it the structural foundation on which every Welsh seats projection rests.

How the World Sees Them

Plaid Cymru

The 12% constituency threshold is achievable across most of Wales given current polling at ~28%; D'Hondt is expected to make Plaid the largest party for the first time.

Welsh Labour

At ~18% nationally, D'Hondt likely delivers seats in every constituency but far fewer than under the old Additional Member System — a structural amplification of Labour's polling collapse.

Smaller parties

Parties polling below 12% in individual constituencies — even with reasonable national shares — risk winning no seats at all, a punishing cliff edge compared to national vote share.