Overview

The single transferable vote (STV) is a ranked voting method used to elect multiple representatives from a single multi-member constituency. Voters list candidates in order of preference. STV aims to produce proportional outcomes by transferring votes from elected or eliminated candidates so that as many ballots as possible contribute to electing someone the voter prefers. In the single-winner case STV becomes the system commonly called instant runoff voting. STV is one type of voting system often used to achieve proportional representation.

How STV works — basic steps

The counting procedure has several recurring stages. Different jurisdictions use modestly different rules, but the core idea is consistent:

  • Determine a quota: the number of votes a candidate needs to be elected (common quotas include the Droop or Hare formulas).
  • Count first-preference votes. Any candidate who reaches the quota is declared elected.
  • If an elected candidate has more votes than the quota, transfer the surplus to remaining candidates according to the next preferences shown on those ballots (transfers can be fractional or by other rules).
  • If no one new meets the quota, eliminate the candidate with the fewest votes and transfer their ballots to the next available preferences.
  • Repeat transfers and eliminations until all seats are filled.

Variants and technical points

Practical implementations differ in quota choice (Droop is common), how surplus votes are transferred (fractional versus random sampling), whether preferences are optional, and whether ballots can become exhausted if no further preferences are expressed. These details affect mechanical outcomes and vote counting complexity but not the method’s central idea of transferring support to reflect voter rankings.

History and use

STV has roots in 19th-century proposals to produce fairer multi-member results and has been adopted in a number of countries. It is widely used in Ireland and Malta, and in various local and national elections elsewhere, including parts of Australia and some municipal elections. Administrations vary the counting rules to balance proportionality, voter expression, and administrative simplicity.

Why STV matters and common criticisms

Proponents praise STV for producing proportional representation while preserving voter choice between individual candidates rather than only between parties. It can encourage broader representation and reduce wasted votes. Critics point to more complex ballots and counting, longer counting times, and potential voter confusion about ranking strategies. The method represents a trade-off between proportionality, voter expressiveness, and operational complexity.

For further technical descriptions and examples of counting procedures see procedural resources or jurisdictional guides such as those linked at the start of this article: voting system overview, proportional representation, and instant runoff voting.