How the Assembly is elected

The Assembly has 60 elected Members (AMs). For an Assembly election, which takes place every four years, each registered voter has two votes.

The first vote is for a local constituency Member. A Member is elected for each of the 40 constituencies in Wales by the 'first past the post' system, the system by which MPs are elected to the House of Commons - i.e. the candidate with the greatest number of votes wins the seat.

The second vote is to elect a regional Member. Regional Members are elected by a form of proportional representation known as the 'Additional Member System’, and voters vote for a political party. Each party must supply a list of candidates for the Additional Member seats in rank order. Wales has five electoral regions, and four Members are elected to serve each region. The electoral regions are based on the European Parliamentary Constituencies created in 1994. Each electoral region covers between 7 and 9 constituencies. The electoral regions are:

• North Wales;
• Mid and West Wales;
• South Wales East;
• South Wales West;
• South Wales Central.

Four additional Members from each of the five regions are elected via the Additional Member System.

The Additional Member System (AMS)

This system goes some way towards ensuring that the overall number of seats held by each political party reflects the share of the vote that the party receives. The system uses the d’Hondt formula method, and works like this:

• The number of votes cast for each party on the electors’ second ballot paper per region is counted.
• This total is divided by the number of constituency seats won by that party under the First Past the Post system, plus one.
• The calculation is then repeated for the second to fourth additional members, in each case dividing the party list vote by the number of constituency seats plus one, and any additional member seats allocated in previous rounds.

Example of the use of the d'Hondt formula for the election of regional Assembly Members

This example covers four parties in a region with eight constituencies

The calculation for the first seat would be as follows. The total number of votes for each party is divided by their division total:

Party D, with 36,000 votes, would be awarded the first additional seat, adding one to their division total. The calculation for the second seat would be:

Party D, with 18,000 votes, would be awarded the second additional seat, adding another one to their division total. The calculation for the third seat would be:

Party C, with 16,000 votes, would be awarded the third additional seat, adding one to their division total. The calculation for the final seat would be:

Party B, with 15,500 votes, would be awarded the final seat. So the total number of seats allocated for each party in this region would be as follows: