What is the single transferable vote?
The single transferable vote, or STV, is a proportional voting system in which voters rank candidates in order of preference in multi-member constituencies. Candidates need a set quota of votes to win. Surplus votes from winners and votes from eliminated candidates are transferred to next preferences until all seats are filled.
Each constituency elects several representatives, often three to six. A quota is calculated from the number of votes and seats. Any candidate reaching the quota is elected. Their extra votes are passed on proportionally to next preferences. If no one reaches the quota, the lowest candidate is eliminated and their votes move on. This repeats until all seats are filled. Counts can take hours.
In the UK, STV is used for Scottish council elections, the Northern Ireland Assembly and Northern Ireland council elections. It is also used in the Republic of Ireland and Malta, and for the Australian Senate. Westminster has never used it for general elections, although some university seats did until 1950. Irish voters have used it since independence in 1922, and it has been retained after referendums.
Supporters say STV produces proportional results while letting voters choose between individual candidates, even within the same party. Critics say counting is complex, constituencies are larger, and it can take days to finish a count. The Liberal Democrats have long backed STV for Westminster elections. Its supporters argue it gives voters more power over individual candidates than list systems do.
Many on the left, especially Greens and Liberal Democrats, support STV as fairer and more proportional than first past the post.
The right is mostly sceptical, arguing STV weakens the single MP link and makes coalitions more likely.
Britain is split. Now you decide.
In Population Decides you can try the seat calculator to compare proportional systems with first past the post.
Play Population Decides freeCommon questions
Where is STV used in the UK?
Scottish council elections and Northern Ireland Assembly and council elections.
Is STV proportional representation?
Yes. It is a form of proportional representation using preferences.
How do you vote with STV?
You number candidates in order of preference, as many or as few as you like.
What does proportional representation aim to do?
Match seats to votes. Proportional systems aim to match each party's share of seats to its share of votes.
Which voting system does the Scottish Parliament use?
Additional Member System. Scotland uses the Additional Member System, which mixes local seats with regional list seats.