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Next UK: English local elections and Northern Ireland Assembly expected May 2027 Preview →
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How to vote

Voting systems

One kingdom,
four ways to count.

The Commons is elected by first past the post, Holyrood by the additional member system, the Senedd by closed party lists and the Northern Ireland Assembly by the single transferable vote. The calculators below run the statutory rules on the real 2026 votes.

First past the post · House of Commons

Most votes
wins the seat.

In each of the 650 constituencies the returning officer declares elected "the candidate to whom the majority of votes has been given" — the largest number, not necessarily more than half.

General election · 2024 · share of votes against share of seats

554 of 650 MPs won with less than half the vote

The lowest winning share was 26.7% (Lab, South West Norfolk).

  • Lab 33.7% votes 63.2% seats · 411
  • Con 23.7% votes 18.6% seats · 121
  • Lib Dem 12.2% votes 11.1% seats · 72
  • SNP 2.5% votes 1.4% seats · 9
  • SF 0.7% votes 1.1% seats · 7
  • Ind 2.0% votes 0.9% seats · 6
  • Reform 14.3% votes 0.8% seats · 5
  • DUP 0.6% votes 0.8% seats · 5
  • Green 6.7% votes 0.6% seats · 4

Hatched: vote share. Solid: seat share. Source: House of Commons Library.

How proportional?

The Gallagher index

The square root of half the summed squared gaps between each party's vote and seat shares, in points: 0 is perfectly proportional. Holyrood and the Senedd are measured on list votes for the parties our sources itemise.

Body System Seats Index
House of Commons, 2024 First past the post 650 23.7
Scottish Parliament, 2026 Additional member system 129 12.7
Senedd, 2026 Closed lists, D'Hondt 96 8.8

Additional member system · Scottish Parliament

Two votes,
one parliament.

One member is returned for each of the 73 constituencies under the simple majority system; seven regional members are returned for each of the eight regions under the additional member system. Each party's regional figure is its regional votes divided by one plus the number of its candidates returned for constituencies in the region, recalculated each time it wins a regional seat; the highest figure takes the next seat.

Try it · Holyrood 2026, region by region

Allocate the seven list seats.

Real list votes and constituency results from May 2026. Parties our source groups as 'other' are left out of the count.

Regional list votes · constituency seats already won

    Rounds · each seat goes to the highest quotient

      Closed lists · Senedd Cymru

      Sixteen constituencies,
      six seats each.

      From 2026 the Senedd has 16 constituencies with six seats each. The first seat goes to the party or individual candidate with the highest "seat allocation figure"; each time a party wins a seat, one is added to its divisor and its figure is recalculated — the D'Hondt method.

      Try it · Senedd 2026

      Fill the six seats.

      Real party votes from May 2026 for the parties our source itemises.

      List votes

        Rounds · each seat goes to the highest quotient

          Single transferable vote · Northern Ireland Assembly and Scottish councils

          Rank them
          all.

          Assembly members are returned for Northern Ireland's parliamentary constituencies — 18 of them, five members each, and each vote is a single transferable vote. Scottish councillors have been elected by STV under the Local Governance (Scotland) Act 2004.

          Try it · Single transferable vote (illustration)

          Rank the candidates; votes move.

          Invented ballots for a multi-member area — not a real count. Choose how many seats to fill and step through the rounds: a candidate who passes the quota is elected and their surplus moves on at a fraction of its value; if nobody reaches it, the last-placed candidate is eliminated and their ballots transfer.

            Mayors and police and crime commissioners

            One vote,
            one winner.

            The Elections Act 2022 (s.13) moved elections for the Mayor of London, elected local authority mayors in England, mayors of combined authority areas and police and crime commissioners to the simple majority system — first past the post.