General · EdgepediaSeptember 17, 20266 min read

Single transferable vote

The single transferable vote (STV) is a proportional representation electoral system in which voters rank candidates in multi-member constituencies, seats are filled by candidates reaching a quota of votes, and surplus or unused votes transfer to other candidates according to voters' later preferences. The system originated in Britain, and elections are now conducted under it, in whole or in part, in Northern Ireland, the Republic of Ireland, Malta, Scotland, and Australia; Americans commonly refer to it as ranked-choice voting when it fills multi-member seats, while Australians call it Hare-Clark.¹

Key fact	Detail
Ballot	Voters number candidates 1, 2, 3 and so on in order of preference; they do not have to number every candidate.¹
Quota	The Droop quota: total valid votes divided by one more than the places to be filled; with 109,525 valid votes and 3 seats the quota is 27,381.25.¹
Surplus transfer	Votes above a winner's quota transfer to next preferences; if 1,000 votes are cast for a winner on a quota of 750, all votes transfer at a value of 0.25 rather than a quarter at full value.²
National use	Ireland and Malta are the only countries to have used STV continuously for their national legislatures since the early 1920s, though Australia has also used STV for its national Senate.³^•¹⁴
Australian record	Tasmania's lower house has used STV since 1909 and the federal Senate since 1949; the two account for almost three-quarters of 68 Australian STV cases by mid-1999.⁴
UK use	Used for Scottish council elections, Northern Ireland Assembly elections, and council elections in Northern Ireland; Scottish counts are usually done electronically.⁵
Proportionality	A 1996 regression analysis of STV variants found Malta the most proportional, followed by Ireland and Tasmania.⁶

How the count works

Voting is simple: the ballot paper lists the candidates, and the voter places a 1 beside their favorite, a 2 beside the next choice, and so on, stopping when they can no longer decide between the candidates.⁷ Counting is more involved. To be elected, a candidate needs a set number of votes, the quota, calculated from the number of vacancies and the number of votes cast.¹ The Electoral Reform Society's handbook defines the quota as the total valid vote divided by one more than the number of places to be filled, calculated to two decimal places; if the division is not exact, the remainder is ignored and 0.01 is added.⁸

Stages of the count. First preferences are sorted and counted, and any candidate with at least a quota is elected. Each subsequent stage either transfers the surplus of a candidate whose vote exceeds the quota, or excludes the candidate or candidates with the fewest votes, whose papers pass to continuing candidates according to next available preferences. The procedure continues until enough candidates have reached the quota to fill all the seats, or the number of candidates left equals the number of unfilled seats.⁸ A ballot paper with no preference marked for any remaining candidate is non-transferable.⁹

Surplus values. When a candidate exceeds the quota, the surplus is shared among the transferable papers. In the Electoral Reform Society's worked example, if 1,000 votes are cast for a winning candidate on a quota of 750, rather than transferring a quarter of the votes at full value, all of the votes transfer at a value of 0.25.²

Origins and adoption

STV originates from the 19th century philosophers Thomas Hare and John Stuart Mill, and Mill was its first major advocate.¹⁰^•³ From the 1880s the British Proportional Representation Society promoted it, and although it was not adopted in Britain, a period of colonial experimentation followed: STV was introduced for all Ireland elections in 1920, in Malta in 1921, and in parts of India in the 1930s.¹¹ Malta's use of STV in elections to representative institutions has been continuous since 1921, predating its independence in 1964.⁴

Adoption beyond these early cases has been limited. STV has been used by some professional organizations, in some local elections in the United States, and for some legislative elections in Australia, but only Ireland and Malta have used it for national legislatures without interruption since the early 1920s.³ In Australia, Tasmania adopted STV for its lower house in 1909 and the Commonwealth Senate followed in 1949; smaller uses include the New South Wales lower house from 1920 to 1925 and upper house since 1978, the South Australian upper house since 1982, the Western Australian upper house since 1989, and the Australian Capital Territory legislature since 1995.⁴ In the United Kingdom it is used for council elections in Scotland and for Northern Ireland Assembly and council elections.⁵

Variants and consequences

STV differs widely in form and application. A 1996 study by David M. Farrell of the University of Manchester, Malcolm Mackerras and Ian McAllister, both then of the University of New South Wales, identified differences on five major characteristics and concluded that no single generic type of STV can be identified. Their regression analysis of the variants found Malta the most proportional system, followed by Ireland and Tasmania, and found that Ireland has the largest party system among the countries using STV, net of other factors.⁶ Malta's experience complicates the proportional label: one analysis of Maltese general elections concludes that STV has, throughout the island's electoral history, created a high degree of disproportionality.¹²

What voters gain. Because constituencies elect several members, voters can choose between candidates of the same party as well as between parties, and can support independent candidates without wasting their vote; Ireland has many independent members of parliament, as do some Scottish councils. Constituencies can follow recognizable local areas such as a whole town or county, giving voters a choice of representatives.¹ The system also lets voters influence the direction their favored party takes, by supporting particular candidates.³

Counting costs. The count is more complex than under first-past-the-post, and in Scotland it is usually done electronically: an e-counting system scans ballot papers, generates reports at each stage, and refers papers it cannot scan to the Returning Officer.⁵ A study of 1,070 Scottish local government elections comprising over 5.4 million ballots found that 27.9% of ballots were exhausted by the final round of counting, though the corresponding weight exhaustion rate was only 7.1%, indicating that many exhausted ballots had already contributed to electing a candidate; the same study found that a substantial number of winners fail to reach quota even after all losing candidates are eliminated.¹³

References

Topic: Encyclopedia › Society and history › Politics and government › Elections and representation › Electoral systems and principles › Voting systems › Ranked and preferential systems › Single transferable vote

Initially written Sep 17, 2026 · Reviewed: Sep 19, 2026; Oct 25, 2026 · Edited: Sep 19, 2026; Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026

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Single transferable vote

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