Guidance for Returning Officers administering a Senedd election

You must allocate the seats within the constituency based on a calculation using the d’Hondt formula. 

The d’Hondt formula sees the number of votes cast in the constituency election for each party divided by the number of constituency seats they have gained plus one. Individual candidates do not have their total votes divided at any stage. They simply win a seat if they have the highest total of votes at any round.

You must calculate the total number of votes given for each party and for each individual candidate. The figure you have after calculating the total number of votes for each party and each individual candidates is known as the seat allocation figure for that party or individual candidate.1

The first seat is allocated to the party or individual candidate with the highest seat allocation figure.2

The seats each party is allocated are filled by the candidates in the order in which their names appear on their party list.

Once an individual candidate has been allocated a seat, or a party has been allocated as many seats as there are candidates on its list, they are removed from the calculation for the allocation of the remaining seats.3

The table gives a worked example where no individual candidates are standing in the constituency:

In the worked example there are six seats available, and these have been allocated as follows: 

Seat 1 – Party A obtained the highest number of votes (116,151) and is therefore entitled to the first available seat. 

Seat 2 – The allocation of the next seat is calculated by dividing the total number of votes each party received by the number of seats it has already been allocated in the constituency, plus one. As a result, Party A’s original total must be divided by two, while the other parties’ totals are still divided by one and so remain the same. This results in this seat being allocated to Party B with its total of 63,769.

Seat 3 – To calculate the allocation of the third seat, both Party A’s and Party B’s total number of votes are divided by two while Party C's and Party's D totals are still divided by one and so remain the same. This results in this seat being allocated to Party C with its total of 61,777.

Seat 4 – To calculate the allocation of the fourth seat, Party A’s, Party B’s and Party Cs total number of votes are divided by two, while Party D's total is still divided by one and so remains the same. This results in this seat being allocated to Party A with its total of 58,075.  

Seat 5 – To calculate the allocation of the fifth seat, Party A's total must now be divided by three, as it now has two seats. Party B's and Party C's total must still be divided by two and Party D's total is still divided by one. This results in this seat being allocated to Party D with its total of 56,479. 

Seat 6 – To calculate the allocation of the sixth seat, Party A's total number of votes is still divided by three, Party B's and Party C’s totals are still divided by two and Party D's total must now be divided by two. This results in the seat being allocated to Party A with its total of 38,717. 

This table gives a worked example where there is an individual candidate standing in the constituency as well as parties:

In the worked example there are six seats available, and these have been allocated as follows: 

Seat 1 – Party A obtained the highest number of votes (116,151) and is therefore entitled to the first available seat. 

Seat 2 – The allocation of the next seat is calculated by dividing the total number of votes each party received by the number of seats it has already been allocated in the constituency, plus one. As a result, Party A’s original total must be divided by two, while the other parties’ totals are still divided by one and so remain the same and the individual candidate’s total also still stands. This results in this seat being allocated to Party B with its total of 63,769.

Seat 3 – To calculate the allocation of the third seat, both Party A’s and Party B’s total number of votes are divided by two while Party C's total is still divided by one and so remain the same and the individual candidate’s total also still stands. This results in this seat being allocated to Party C with its total of 61,777.

Seat 4 – To calculate the allocation of the fourth seat, Party A’s, Party B’s and Party Cs total number of votes are divided by two, while the individual candidate’s total still stands . This results in this seat being allocated to Party A with its total of 58,075.

Seat 5 – To calculate the allocation of the fifth seat, Party A's total must now be divided by three, as it now has two seats. Party B's and Party C's total must still be divided by two and the individual candidate’s total still stands. This results in this seat being allocated to the individual candidate with their total of 56,479. 

Seat 6 – To calculate the allocation of the sixth seat, Party A's total is divided by three and Party B's and Party C’s totals are each divided by two. The individual candidate has been allocated a seat and cannot be allocated further seats. This results in the seat being allocated to Party A with its total of 38,717.