While millions of votes cast in Sunday's municipal elections will make it clear how big the share of votes for each party is, translating these votes into seats on the municipal council is slightly more complicated.
Going from votes to seats in Belgium's federal and various regional parliaments requires a complex calculation, known as the D'Hondt method. On the municipal level, however, the seat distribution works with a different system.
The number of seats on a municipal council depends on how many people live in the municipality: the minimum number in Belgium is seven, while the maximum is 55.
Since thousands of votes have to be converted into a few seats on every municipality's council, a method to do this as fairly as possible is needed. As rounding up or down will inevitably lead to issues, simply applying the percentages to the total number of seats is not enough.
The Imperiali method
The system is named after Pierre Guillaume Imperiali des Princes de Francavilla, a Catholic Belgian senator who proposed it in 1921 to disadvantage small political lists compared to the lists with a significant number of votes.
The Imperiali method distributes the number of seats according to the votes cast for the participating parties. The system gives larger parties an advantage, meaning that it no longer provides proportional representation. It is therefore not used at the federal or regional levels, but is still in place for municipal elections in Belgium.
Step 1: Calculating the vote count for each list
The vote count is the total number of votes for each list (this takes into account votes for lists as well as preferential ones).
Step 2: Calculating the electoral quota
The electoral quota is the minimum number of votes required to obtain a seat. The Imperiali method calculates the electoral quota in three steps:
- Divide the vote totals of all lists above the electoral threshold first by 2, then by 3, 4, 5, etc.
- Rank the obtained quotients in order of size until there are as many quotients in total as there are seats to be distributed in that constituency.
- The electoral quota is the last quotient to be ordered in this way.
Step 3: Calculating the number of seats per list
Any list will get as many seats as the number of times the vote count can be divided by the electoral quota.
If two quotients are the same, the quotient that is the result of the largest divisor (= the party with the most votes) is allocated the first seat. In practice, however, this will occur very rarely. If the vote counts are also equal, the seat goes to the candidate with the highest number of preferential votes. If that too is equal, the youngest candidate is elected.
Example:
The Flemish Parliament provides the example below (but in Dutch) to put concrete figures to the abstract calculation method. The table shows how this calculation would be used if 1,960 valid votes were cast in electoral district X, where four lists (1, 2, 3 and 4) were running and nine seats were to be allocated (indicated in Roman numerals).
The allocation of the nine seats is determined by the nine highest quotients (in this case: 420, 280, 216, 210, 180, 168, 164, 144 and 140). This way, five seats are allocated to list 1, two seats to list 2, and one seat each to lists 3 and 4.
If a list has obtained more seats than it has candidates, the unallocated seats will be further distributed among the other lists by continuing the rules for seat distribution as described above.
