Politics & media · Electoral system

How votes become seats

How the UK electoral system translates votes into political power — and what would change under alternative systems.

Put this in scale: 33.7% of the vote, 63.2% of the seats

The question this section answers

Britain elects one MP per constituency, and the candidate with the most votes wins. This page sets out what that produces — in the 2024 result, and across every election since 1979.

It takes no position on whether the system should change. It reports what the official results show, says where a measure is an analytical convention rather than an official statistic, and gives the arguments made for the current system the same weight as the disparities it produces.

33.7%

of votes went to the governing party in 2024

Labour, on a turnout of 59.7% of registered electors.

63.2%

of seats went to the governing party

411 of 650 seats in the House of Commons.

823,522

votes per seat won by Reform UK

Labour won a seat for every 23,622.

Every 100 votes

Every 100 seats

  • Labour
  • Conservative
  • Reform UK
  • Liberal Democrat
  • Green
  • All other candidates
  • Scottish National Party
  • Sinn Féin
  • Plaid Cymru
  • Democratic Unionist Party
  • Alliance Party of Northern Ireland
  • Ulster Unionist Party
  • Social Democratic and Labour Party

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009), dataset version 3 March 2026 (dataset revision; record of dataset changes updated 5 January 2026).

How the system works

The UK is divided into 650 constituencies. Each elects one MP. Voters mark a single cross for one candidate, and the candidate with more votes than any other wins the seat. There is no requirement to reach 50%, and no second round.

This is First Past the Post. It is used for elections to the House of Commons and for local elections in England and Wales. Other elections in the UK use different systems entirely — Northern Ireland and Scottish local councils use the Single Transferable Vote, the Scottish Parliament uses an additional member system, and from May 2026 the Senedd uses a closed-list proportional system.

Official statistic

A real seat won on the smallest share of the vote, 2024

26.7%

South West Norfolk was won on 26.7% of the votes cast there — 11,847 votes of 44,335. Just under three-quarters of voters in that constituency chose someone else, and under this system that is a valid and normal result rather than an anomaly.

Shown instead of an invented illustration because a real constituency is citable. The winning share in a seat depends on how many candidates stand and how close they are — it is not a measure of an MP’s support in the country.

House of Commons Library, General election 2024 results (CBP-10009) · Electoral Commission, How MPs are elected ↗ · Commons Library CBP-10879 ↗

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009).

Britain already uses several voting systems

Four different electoral systems are already in use across the UK. A voter in Northern Ireland ranks candidates for the Assembly and their council, and marks a single cross for Westminster. A voter in Scotland uses three different systems across the three bodies they elect. Whatever the merits of changing the Westminster system, doing so would not require Britain to attempt something it has never done.

  • House of Commons

    First Past the Post

    650 single-member constituencies. One cross, most votes wins, no threshold and no second round.

  • Local councils in England and Wales

    First Past the Post

    Single- and multi-member wards, each elected on the same plurality basis.

  • Senedd Cymru / Welsh Parliament

    Closed-list proportional representationsince May 2026

    96 Members across 16 constituencies, six per constituency. Voters cast one vote for a party list or an independent, and seats are allocated by the D’Hondt method. This replaced the previous additional member system.

  • Scottish Parliament

    Additional member system

    Constituency MSPs elected by First Past the Post, plus regional MSPs allocated to bring each region closer to proportionality. Voters cast two votes.

  • Northern Ireland Assembly

    Single Transferable Vote

    Multi-member constituencies with ranked ballots. Candidates are elected on reaching a quota, with surpluses and eliminated candidates’ votes transferred by preference.

  • Local councils in Northern Ireland

    Single Transferable Vote

    The same ranked, multi-member method used for the Assembly.

  • Local councils in Scotland

    Single Transferable Vote

    Multi-member wards with ranked ballots, used since 2007.

Wales changed system in May 2026

The 2026 Senedd election was the first conducted under a closed proportional list system. Wales now has 96 Members of the Senedd across 16 constituencies — 6 per constituency — with one vote for a party list or an independent and seats allocated by the D’Hondt method. Turnout was 51.6%, higher than at all previous senedd and welsh assembly elections. 16- and 17-year-olds and qualifying foreign nationals resident in Wales could vote.

Electoral Commission, Post count statement – 2026 Senedd election (8 May 2026) · Senedd constituencies guidance ↗

Last verified 16 August 2026. Data: House of Commons Library, Electoral systems across the UK (SN04458); Electoral Commission Senedd guidance and post-count statement.

Votes and seats since 1979

Seat outcomes under this system depend on where votes are cast, not only on how many there are. A party whose support is concentrated in particular places converts votes into seats efficiently; a party whose support is spread evenly does not. The Commons Library sets this mechanism out in its “turning votes into seats” briefings.

How parties are grouped in this series.The 1918–2019 source records five groups only: Conservative, Liberal (covering the Liberal Party, the SDP–Liberal Alliance and the Liberal Democrats), Labour, the SNP and Plaid Cymru together, and all other parties. Reform UK, the Greens, UKIP and the Northern Ireland parties are inside “all other parties” before 2024. To keep the series comparable, 2024 is shown on the same five groups here; the 2024 case study below uses full party detail.

Seat share minus vote share, by party group, 1979–2024

Seat share minus vote share, in percentage points. Bars right of the centre line mean a party held a larger share of seats than of votes; bars left mean the reverse. The axis runs −30 to +30.

1979

  • Conservative+9.5pp
  • Labour+5.4pp
  • Liberal / Alliance / Liberal Democrat-12.1pp
  • All other parties-1.4pp
  • SNP and Plaid Cymru-1.4pp

1983

  • Conservative+18.6pp
  • Labour+4.6pp
  • Liberal / Alliance / Liberal Democrat-21.8pp
  • All other parties-0.5pp
  • SNP and Plaid Cymru-0.9pp

1987

  • Conservative+15.5pp
  • Labour+4.4pp
  • Liberal / Alliance / Liberal Democrat-19.2pp
  • All other parties+0.0pp
  • SNP and Plaid Cymru-0.7pp

1992

  • Conservative+9.7pp
  • Labour+7.2pp
  • Liberal / Alliance / Liberal Democrat-14.9pp
  • All other parties-0.8pp
  • SNP and Plaid Cymru-1.3pp

1997

  • Labour+20.2pp
  • Conservative-5.6pp
  • Liberal / Alliance / Liberal Democrat-9.8pp
  • All other parties-3.0pp
  • SNP and Plaid Cymru-1.0pp

2001

  • Labour+21.8pp
  • Conservative-6.5pp
  • Liberal / Alliance / Liberal Democrat-10.4pp
  • All other parties-3.8pp
  • SNP and Plaid Cymru-1.1pp

2005

  • Labour+19.8pp
  • Conservative-1.7pp
  • Liberal / Alliance / Liberal Democrat-12.4pp
  • All other parties-4.8pp
  • SNP and Plaid Cymru-0.8pp

2010

  • Conservative+11.0pp
  • Labour+10.7pp
  • Liberal / Alliance / Liberal Democrat-14.3pp
  • All other parties-6.6pp
  • SNP and Plaid Cymru-0.8pp

2015

  • Conservative+14.0pp
  • Labour+5.1pp
  • All other parties-16.2pp
  • Liberal / Alliance / Liberal Democrat-6.6pp
  • SNP and Plaid Cymru+3.7pp

2017

  • Conservative+6.4pp
  • Labour+0.3pp
  • Liberal / Alliance / Liberal Democrat-5.5pp
  • All other parties-3.7pp
  • SNP and Plaid Cymru+2.5pp

2019

  • Conservative+12.5pp
  • Labour-1.0pp
  • Liberal / Alliance / Liberal Democrat-9.9pp
  • All other parties-5.3pp
  • SNP and Plaid Cymru+3.6pp

2024

  • Labour+29.5pp
  • All other parties-22.1pp
  • Conservative-5.1pp
  • Liberal / Alliance / Liberal Democrat-1.1pp
  • SNP and Plaid Cymru-1.2pp
View as table
ElectionConservativeLabourLiberal / Alliance / Liberal DemocratAll other partiesSNP and Plaid Cymru
1979+9.5pp+5.4pp-12.1pp-1.4pp-1.4pp
1983+18.6pp+4.6pp-21.8pp-0.5pp-0.9pp
1987+15.5pp+4.4pp-19.2pp+0.0pp-0.7pp
1992+9.7pp+7.2pp-14.9pp-0.8pp-1.3pp
1997+20.2pp-5.6pp-9.8pp-3.0pp-1.0pp
2001+21.8pp-6.5pp-10.4pp-3.8pp-1.1pp
2005+19.8pp-1.7pp-12.4pp-4.8pp-0.8pp
2010+11.0pp+10.7pp-14.3pp-6.6pp-0.8pp
2015+14.0pp+5.1pp-16.2pp-6.6pp+3.7pp
2017+6.4pp+0.3pp-5.5pp-3.7pp+2.5pp
2019+12.5pp-1.0pp-9.9pp-5.3pp+3.6pp
2024+29.5pp-22.1pp-5.1pp-1.1pp-1.2pp

House of Commons Library, General election results from 1918 to 2019 (CBP-8647) · House of Commons Library, General election 2024 results (CBP-10009) · Turning votes into seats, 2019 ↗

The Gallagher Index

Official statisticEstablished academic measure, computed here from official results

The Gallagher Index is an established measure of the difference between parties’ vote shares and seat shares. Higher values indicate a larger aggregate difference. It is not a fairness score, and this site does not present it as one — the formula is in the methodology panel below.

Gallagher Index, UK general elections 1979–2024

Five-group basis throughout, so the series is internally consistent. Computed from the Commons Library results.

View as table
ElectionValue
7911.61
8320.57
8717.74
9213.59
9716.52
0117.93
0516.92
1015.56
1516.43
176.76
1912.18
2426.36

The Gallagher Index ranged from 2.86 in 1951 to 26.36 in 2024 across the period.

How fragmented are voters, and how fragmented is Parliament?

Official statisticLaakso–Taagepera measure, computed from official results

The effective number of parties counts parties weighted by their size, so a party with 2% of the vote barely registers and two evenly matched parties count as two. Computed on vote shares it describes how divided voters are; computed on seat shares it describes how divided Parliament is. The gap between the two lines is the electoral system at work.

Effective number of parties, UK general elections 1979–2024

Dark bar: effective number of electoral parties, from vote shares. Pale bar: effective number of parliamentary parties, from seat shares. Five-group basis throughout.

View as table
ElectionValueSecond series
792.862.15
833.112.09
873.072.17
923.052.27
973.192.12
013.282.17
053.522.46
103.612.58
153.632.54
172.852.47
193.172.38
243.852.22

In 2024 the effective number of electoral parties was 3.85 and the effective number of parliamentary parties was 2.22.

Voters have become steadily more divided across parties since 1979, while Parliament has not divided at anything like the same rate. On this measure 2024 produced the widest gap in the series.

Last verified 16 August 2026. Data: House of Commons Library, General election results from 1918 to 2019 (CBP-8647); House of Commons Library, General election 2024 results (CBP-10009).

The 2024 election in detail

Full party detail, from the Commons Library’s constituency dataset. This is the only place on the page where Reform UK, the Greens and the Northern Ireland parties appear separately, because 2024 is the only election for which the source supports it.

Vote share and seat share by party, 2024

Turnout 59.74% of registered electors. 28,809,340 valid votes across 650 constituencies.

  • Labour

    Votes33.7%
    Seats63.2%
  • Conservative

    Votes23.7%
    Seats18.6%
  • Reform UK

    Votes14.3%
    Seats0.8%
  • Liberal Democrat

    Votes12.2%
    Seats11.1%
  • Green

    Votes6.8%
    Seats0.6%
  • All other candidates

    Votes3.8%
    Seats1.2%
  • Scottish National Party

    Votes2.5%
    Seats1.4%
  • Sinn Féin

    Votes0.7%
    Seats1.1%
  • Plaid Cymru

    Votes0.7%
    Seats0.6%
  • Democratic Unionist Party

    Votes0.6%
    Seats0.8%
  • Alliance Party of Northern Ireland

    Votes0.4%
    Seats0.2%
  • Ulster Unionist Party

    Votes0.3%
    Seats0.2%
  • Social Democratic and Labour Party

    Votes0.3%
    Seats0.3%

Both bars run on the same 0–100% scale. The paler bar is vote share, the solid bar seat share.

View as table
PartyVotesVote shareSeatsSeat shareSeat share − vote share
Labour9,708,71633.7%41163.2%+29.5pp
Conservative6,828,92523.7%12118.6%-5.1pp
Reform UK4,117,61014.3%50.8%-13.5pp
Liberal Democrat3,519,14312.2%7211.1%-1.1pp
Green1,944,5016.8%40.6%-6.1pp
All other candidates1,089,0963.8%81.2%-2.5pp
Scottish National Party724,7582.5%91.4%-1.1pp
Sinn Féin210,8910.7%71.1%+0.3pp
Plaid Cymru194,8110.7%40.6%-0.1pp
Democratic Unionist Party172,0580.6%50.8%+0.2pp
Alliance Party of Northern Ireland117,1910.4%10.2%-0.3pp
Ulster Unionist Party94,7790.3%10.2%-0.2pp
Social Democratic and Labour Party86,8610.3%20.3%+0.0pp

Two parties, similar vote shares, very different seat counts

Reform UK received 14.3% of votes and won 5 seats. The Liberal Democrats received 12.2% and won 72.

The gap is a function of geography. Liberal Democrat support was concentrated in a set of target seats; Reform UK’s was spread widely, finishing second in many constituencies and first in few. The Commons Library published a dedicated analysis of how Reform and the Greens performed in 2024.

House of Commons Library, 2024 general election: performance of Reform and the Greens

Both Reform UK and the Green Party won their highest-ever number of seats in 2024, while holding seat shares well below their vote shares — the green party received 6.8% of votes and won 4 seats.

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009), dataset version 3 March 2026 (dataset revision; record of dataset changes updated 5 January 2026).

Votes per elected MP

Votes cast per seat won, by party, 2024

Total votes divided by seats won, for parties that won at least one seat. Bars share one scale.

  • Labour (411 seats)23,622
  • Sinn Féin (7 seats)30,127
  • Democratic Unionist Party (5 seats)34,412
  • Social Democratic and Labour Party (2 seats)43,430
  • Plaid Cymru (4 seats)48,703
  • Liberal Democrat (72 seats)48,877
  • Conservative (121 seats)56,437
  • Scottish National Party (9 seats)80,529
  • Ulster Unionist Party (1 seats)94,779
  • Alliance Party of Northern Ireland (1 seats)117,191
  • All other candidates (8 seats)136,137
  • Green (4 seats)486,125
  • Reform UK (5 seats)823,522
View as table
PartyVotesSeatsVotes per seat
Labour9,708,71641123,622
Conservative6,828,92512156,437
Reform UK4,117,6105823,522
Liberal Democrat3,519,1437248,877
Green1,944,5014486,125
All other candidates1,089,0968136,137
Scottish National Party724,758980,529
Sinn Féin210,891730,127
Plaid Cymru194,811448,703
Democratic Unionist Party172,058534,412
Alliance Party of Northern Ireland117,1911117,191
Ulster Unionist Party94,779194,779
Social Democratic and Labour Party86,861243,430

What this measure does and does not mean

This is a consequence of where votes were cast, not of votes being weighted differently. Every vote counts once. A party whose support is concentrated wins seats with fewer votes each; a party whose support is spread thinly across many constituencies can accumulate a large national total without winning constituencies. The ratio describes the geography of support, not the value of a ballot.

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009).

Votes that did not elect anyone

This section deliberately avoids the phrase “wasted votes”. Whether a vote for a losing candidate was wasted is a judgement about what a vote is for; that it did not elect anybody is a fact. Two different measures are involved and they are kept apart.

Official statistic

Primary measure: votes for candidates who were not elected

For every constituency, the valid votes cast minus the votes for the winning candidate. Objective, and computed directly from the official results.

57.7%

16,626,960 votes in 2024

UK Facts analytical convention

Secondary measure: winners’ votes beyond what they needed

Votes received by winning candidates above the number required to beat the runner-up. An established convention in the literature, but not an official category — so it is labelled as an analytical measure and never headlined.

4,568,570

surplus votes in 2024

Never add these two together without saying so

Combining the primary and secondary measures produces a single large number that is sometimes quoted as the share of “votes that made no difference”. That combined figure is a UK Facts analytical measure, not an official statistic, and this page does not headline it. The two measures answer different questions and rest on different assumptions about what a vote is supposed to achieve.

Valid votes cast in 2024, split by whether the candidate was elected
  • Votes for candidates who were elected12,182,380 votes
  • Votes for candidates who were not elected16,626,960 votes

House of Commons Library, General election 2024 results (CBP-10009)

How close were the results?

UK Facts analytical conventionMargin bands are a UK Facts convention, not an official category
Constituencies by winning margin, 2024
  • Ultra-safe (over 30 point margin)95 seats

    14.6% of seats · 7,014,028 registered electors (14.5%)

  • Safe (15–30 point margin)212 seats

    32.6% of seats · 15,665,083 registered electors (32.5%)

  • Competitive (5–15 point margin)228 seats

    35.1% of seats · 16,953,204 registered electors (35.2%)

  • Marginal (0–5 point margin)115 seats

    17.7% of seats · 8,591,897 registered electors (17.8%)

View as table
Margin bandSeatsShare of seatsRegistered electorsShare of electors
Ultra-safe9514.6%7,014,02814.5%
Safe21232.6%15,665,08332.5%
Competitive22835.1%16,953,20435.2%
Marginal11517.7%8,591,89717.8%

Seats and electors are shown separately because they answer slightly different questions: how many constituencies fall in each band, and how many registered electors live in them. “Electorate” here means registered electors, not residents.

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009).

What did your vote actually buy?

Take the votes actually cast in 2024 and distribute 650 seats by a named allocation method. Switch between methods to see how much the choice of formula — not just the choice between proportional and non-proportional systems — changes the answer.

Allocation method

Largest remainder, Hare quota. Divide total votes by the number of seats to get a quota. Each party gets one seat per whole quota it holds. Any seats still unallocated go to the parties with the largest remainders. Close to neutral between large and small parties, which is why it is the default here — it answers the "as closely as possible to vote share" question with the least distortion of its own.

  • Labour33.7% of votes → 411 seats actual
  • Conservative23.7% of votes → 121 seats actual
  • Reform UK14.3% of votes → 5 seats actual
  • Liberal Democrat12.2% of votes → 72 seats actual
  • Green6.7% of votes → 4 seats actual
  • All other candidates3.8% of votes → 8 seats actual
  • Scottish National Party2.5% of votes → 9 seats actual
  • Sinn Féin0.7% of votes → 7 seats actual
  • Plaid Cymru0.7% of votes → 4 seats actual
  • Democratic Unionist Party0.6% of votes → 5 seats actual
  • Alliance Party of Northern Ireland0.4% of votes → 1 seats actual
  • Ulster Unionist Party0.3% of votes → 1 seats actual
  • Social Democratic and Labour Party0.3% of votes → 2 seats actual

Bars share one scale, set by the largest seat count shown. Total seats allocated: 650.

This is an illustration, not a prediction. Under a different electoral system, voters, parties and campaigns would behave differently. It shows how the same national votes would map to seats under the named allocation method — not what the result “would have been”.

And a UK-wide allocation is artificial. Parties do not all contest every part of the UK, and real proportional systems normally use regional or multi-member constituencies rather than treating the whole country as one constituency — which produces less proportional results than the figures here.

Largest remainder, Hare quota — the default allocation, in full

This is an illustration, not a prediction. Under a different electoral system, voters, parties and campaigns would behave differently. It shows how the same national votes would map to seats under the named allocation method — not what the result “would have been”.

View as table
PartyVote shareSeats won in 2024Seats under Largest remainderDifference
Labour33.7%411219-192
Conservative23.7%121154+33
Reform UK14.3%593+88
Liberal Democrat12.2%7279+7
Green6.7%444+40
All other candidates3.8%825+17
Scottish National Party2.5%916+7
Sinn Féin0.7%75-2
Plaid Cymru0.7%440
Democratic Unionist Party0.6%54-1
Alliance Party of Northern Ireland0.4%13+2
Ulster Unionist Party0.3%12+1
Social Democratic and Labour Party0.3%220

What the threshold toggle shows

Applying a 5% threshold to a UK-wide allocation excludes 8 of the parties on the ballot, including the Scottish National Party, Plaid Cymru and every Northern Ireland party — parties that win seats precisely because their support is concentrated in one nation. It is a concrete illustration of why real proportional systems in multi-national states use regional districts rather than one national pool, and why the design details of a system matter as much as the choice of family.

A mixed-member illustration: keep every constituency MP, add top-ups

The compromise most often proposed for the UK keeps constituency MPs and adds top-up seats to bring the chamber closer to national vote shares. Rather than assume a top-up proportion, this model computes the smallest chamber in which no party is over-represented while every 2024 constituency winner keeps their seat.

1,220 seats

650 constituency MPs plus 570 top-up seats

That is the arithmetic of compensatory top-ups: they can only correct a disparity by adding seats, so the more skewed the constituency result, the larger the chamber has to become. Labour would need no top-up seats at all, because it is the party the constituency result over-represented.

View as table
PartyVote shareConstituency seatsTop-up seatsTotalShare of chamber
Labour33.7%411041133.7%
Conservative23.7%12116828923.7%
Reform UK14.3%517017514.3%
Liberal Democrat12.2%727714912.2%
Green6.7%478826.7%
All other candidates3.8%838463.8%
Scottish National Party2.5%922312.5%
Sinn Féin0.7%7290.7%
Plaid Cymru0.7%4480.7%
Democratic Unionist Party0.6%5270.6%
Alliance Party of Northern Ireland0.4%1450.4%
Ulster Unionist Party0.3%1340.3%
Social Democratic and Labour Party0.3%2240.3%

This model is the least realistic on the page. Real mixed-member systems give voters two votes — one for a constituency candidate, one for a party list — and many people split them between parties. The 2024 election had no second vote, so this model reuses the single First Past the Post vote for both purposes, which no real system does. It also enlarges the Commons rather than reducing the number of constituencies, which is one of several designs a real reform could take.

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009).

The alternatives

Five systems, including the current one. Advantages and trade-offs are the arguments made about each system, not this site’s assessment of them.

  • First Past the Post (current)

    Proportional: No
    1. 1The country is divided into single-member constituencies.
    2. 2Voters mark one cross for one candidate.
    3. 3The candidate with the most votes wins the seat. There is no 50% requirement.

    Where it is used: The House of Commons; local councils in England and Wales.

    Advantages claimed

    • One identifiable local MP per area, with a direct constituency link.
    • Simple to vote, simple to count, results usually declared overnight.
    • Tends to produce single-party majorities and so clear lines of accountability.

    Trade-offs

    • Seat shares can diverge substantially from vote shares.
    • Parties with evenly spread support win few seats relative to their votes.
    • Creates an incentive to vote tactically rather than sincerely.
  • Alternative Vote

    Proportional: No
    1. 1Single-member constituencies, as now.
    2. 2Voters rank candidates in order of preference.
    3. 3If nobody has more than half of first preferences, the last-placed candidate is eliminated and their votes transferred, until someone passes 50%.

    Where it is used: Not used for any UK public election. Used in Australia’s House of Representatives.

    Advantages claimed

    • Every winning candidate has majority support among voters who expressed a preference between the final two.
    • Reduces the incentive to vote tactically, because a lower preference still counts.
    • Keeps the single-member constituency link intact.

    Trade-offs

    • It is not a proportional system, and can produce results as disproportionate as FPTP or more so.
    • Counting is more complex and slower.

    Put to the UK. Put to a UK-wide referendum on 5 May 2011 and rejected: 67.9% voted No, 32.1% Yes, on a turnout of 42.0%. The No vote was in the majority in every region of the UK.

  • Single Transferable Vote

    Proportional: Yes
    1. 1Multi-member constituencies, each electing several representatives.
    2. 2Voters rank candidates, and may rank candidates from different parties.
    3. 3Candidates reaching a quota are elected; surplus votes and votes from eliminated candidates transfer by preference.

    Where it is used: The Northern Ireland Assembly, Northern Ireland councils and Scottish councils. Also the Republic of Ireland.

    Advantages claimed

    • Broadly proportional outcomes while keeping a geographic constituency link.
    • Voters choose between candidates of the same party, not just between parties.
    • Very few votes are cast for candidates who are neither elected nor transferred.

    Trade-offs

    • Constituencies are larger, so the link to a single named representative is weaker.
    • Counting is substantially more complex and takes longer.
    • Can create competition between candidates of the same party.
  • Additional member / mixed-member

    Proportional: Partly
    1. 1Voters cast two votes: one for a constituency representative, one for a party list.
    2. 2Constituency seats are decided by First Past the Post.
    3. 3Additional list seats are allocated to bring each region closer to proportionality.

    Where it is used: The Scottish Parliament, and the Senedd before 2026. Also Germany and New Zealand.

    Advantages claimed

    • Keeps a named constituency representative while correcting much of the disparity between votes and seats.
    • Usually the most-discussed compromise in UK debate, because it changes least about the constituency link.

    Trade-offs

    • Creates two classes of representative, elected on different bases.
    • How proportional it is depends heavily on the ratio of constituency to list seats.
    • Closed lists give parties, not voters, control over who fills the list seats.
  • Party-list proportional representation

    Proportional: Yes
    1. 1Multi-member districts, or one national district.
    2. 2Voters cast a vote for a party list; in open-list variants they can also express a preference between that party’s candidates.
    3. 3Seats are allocated in proportion to votes, by a named divisor or quota method.

    Where it is used: The Senedd from May 2026, using closed lists and the D’Hondt method.

    Advantages claimed

    • Produces the closest match between vote shares and seat shares.
    • Small parties with dispersed support gain representation.

    Trade-offs

    • Closed lists weaken or remove the link between a voter and an individual representative.
    • Thresholds and district size materially change the outcome — the label "list PR" covers systems that behave quite differently.
    • Coalition government becomes the norm rather than the exception.

Side by side

Comparative assessment, not official statistics. These ratings summarise the standard arguments about each system as set out in House of Commons Library briefings. They are judgements about a debate, not measurements, and reasonable people rate several of these cells differently.

Proportionality

How closely seat shares track vote shares.

  • First Past the PostLow
  • Alternative VoteLow
  • Single Transferable VoteHigh
  • Additional member / mixed-memberMedium
  • Party-list proportional representationHigh

Local representative link

Whether each voter has one identifiable representative for their area.

  • First Past the PostHigh
  • Alternative VoteHigh
  • Single Transferable VoteMedium
  • Additional member / mixed-memberHigh
  • Party-list proportional representationLow

Simplicity for voters and counters

How easy the ballot is to complete and the count to conduct and observe.

  • First Past the PostHigh
  • Alternative VoteMedium
  • Single Transferable VoteLow
  • Additional member / mixed-memberMedium
  • Party-list proportional representationMedium

Likelihood of single-party government

How often one party wins a governing majority on its own.

  • First Past the PostHigh
  • Alternative VoteHigh
  • Single Transferable VoteLow
  • Additional member / mixed-memberLow
  • Party-list proportional representationLow

Incentive to vote tactically

How much the system rewards voting for a party other than your first choice.

  • First Past the PostHigh
  • Alternative VoteLow
  • Single Transferable VoteLow
  • Additional member / mixed-memberMedium
  • Party-list proportional representationLow

Choice between candidates of the same party

Whether voters, rather than parties, decide which of a party’s candidates is elected.

  • First Past the PostLow
  • Alternative VoteLow
  • Single Transferable VoteHigh
  • Additional member / mixed-memberVaries
  • Party-list proportional representationVaries

Representation of smaller parties

How readily a party with dispersed national support wins seats.

  • First Past the PostLow
  • Alternative VoteLow
  • Single Transferable VoteHigh
  • Additional member / mixed-memberMedium
  • Party-list proportional representationHigh

Last verified 16 August 2026. Data: House of Commons Library, Electoral systems across the UK (SN04458); House of Commons Library, Alternative Vote referendum 2011 (RP11-44).

Who wants to change it?

Every position here links to the party’s own document. Where a party’s current position could not be established from an accessible party source it is marked as unverified rather than inferred — two rows are in that state at the moment.

Why this has three columns and not one

Labour is the row that shows why this table has three separate columns rather than one. Conference voted in 2022 that the party must commit to proportional representation in its next manifesto. The 2024 manifesto contains no reference to the electoral system at all — verified by searching the published document. And there is no government programme to change it. Conference position, manifesto commitment and government policy are three different things, and on this issue they do not agree with each other.

  • Liberal Democrats

    Supports PR

    Support replacing First Past the Post with proportional representation. Existing party policy is the Single Transferable Vote for MPs.

    Preferred system: Single Transferable Vote

    2024 manifesto
    Official policy

    Campaigns for proportional representation, described as making seats won match votes cast.

    Party source ↗

    Verified 2026-08-16

    Conference position
    Conference position

    Autumn 2024 conference motion F29 calls on the Government to replace First Past the Post for UK general elections with proportional representation by the Single Transferable Vote, and to introduce STV for local councillors in England.

    Party source ↗

    Verified 2026-08-16

    Government policy
    Not in government

    Other documents

    Internal consultation

    The Spring 2026 'Defending Democracy' consultation paper states on its face that it does not represent agreed party policy, while separately identifying existing policy as STV for MPs.

    Party source ↗

    Verified 2026-08-16

  • Green Party of England and Wales

    Supports PR

    Support replacing First Past the Post with a proportional system. The manifesto does not name a specific system.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Official policy

    Elected Greens will push for replacing the first past the post system for parliamentary elections with a fair and proportional voting system.

    Party source ↗

    Verified 2026-08-16

    Conference position
    None recorded
    Government policy
    Not in government
  • Labour

    Internal support, no commitment

    Party conference voted in 2022 for a commitment to proportional representation. The 2024 general election manifesto contained no such commitment, and there is no government programme to change the Westminster voting system.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Official policy

    The manifesto contains no reference to proportional representation, First Past the Post, the electoral system or electoral reform. It does commit to House of Lords reform and votes at 16.

    Party source ↗

    Verified 2026-08-16

    Conference position
    Conference position

    The 2022 conference carried a motion resolving that Labour must commit to introducing proportional representation for general elections in the next manifesto, and change the voting system during its first term in office.

    Party source ↗

    Verified 2026-08-16

    Government policy
    Official policy

    No programme to introduce proportional representation for Westminster elections.

    Party source ↗

    Verified 2026-08-16

  • Conservative

    Needs verificationOpposes changing the system

    Historically defend First Past the Post for Westminster elections. The current position has not been verified against a post-2024 party source.

    Preferred system: First Past the Post

    2024 manifesto
    Not verified — checking
    Conference position
    None recorded
    Government policy
    Historical position

    The then-Government position recorded by the House of Commons Library was that First Past the Post should be retained for Westminster elections.

    Party source ↗

    Verified 2026-08-16

  • Reform UK

    Needs verificationNot verified — checking

    Position to be verified against the latest party manifesto or policy statement.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Not verified — checking
    Conference position
    None recorded
    Government policy
    Not in government
  • Scottish National Party

    Needs verificationNot verified — checking

    Westminster electoral-reform commitment to be verified against the latest party manifesto.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Not verified — checking
    Conference position
    None recorded
    Government policy
    Not in government

A document on a party website is not automatically that party’s policy.Each entry carries the level of the document it comes from: official policy, a conference position, an internal consultation, or a historical position. The Liberal Democrats’ Spring 2026 consultation paper, for example, states on its own face that it does not represent agreed party policy — so it is recorded at consultation level, separately from the party’s actual policy of the Single Transferable Vote.

Last verified 16 August 2026. Data: Each party’s own published manifesto, policy page, conference motion or consultation paper.

What First Past the Post does well

The arguments below are the ones made by the system’s supporters, including in the Government position recorded by the Commons Library. They are presented here at the same length and weight as the disparities above, because a page that reported only one side would not be describing the debate.

A constituency link

Every voter has one identifiable local MP responsible for their area, who holds surgeries and takes up individual cases. Supporters argue this accountability is weakened by systems with multi-member districts or party lists.

Simplicity

One cross, one count, a result usually declared overnight. Ballot papers are easy to complete and hard to spoil, and the count is straightforward to observe and to challenge.

Decisive outcomes

The system tends to convert a lead in seats into a working majority, which supporters argue produces governments able to deliver a manifesto and voters able to remove them at the next election.

Arguments as recorded in House of Commons Library, Debate on electoral reform (CDP-2019-0094)

Governments and the share of the vote they were elected on

Every postwar government has been formed by a party — or a coalition — that won a plurality of seats. Most were formed on well under half the votes cast. That is how a constituency-based plurality system is designed to work: it converts a lead in seats into a working majority, which is the source both of the decisiveness its supporters value and of the disparities its critics point to.

Most seats is not most votes, and neither is the same as forming a government

Most seats is not the same as most votes, and neither guarantees forming a government. In 1951 and again in February 1974 the party with the most votes did not form the government. In 2010 and 2017 no party had a majority at all, and the government was a coalition and a confidence-and-supply arrangement respectively. Those four elections are marked on the chart.

Vote share of the party forming the government, UK general elections 1945–2024

Vote share of the party that formed the government, with a 50% reference line. Marked elections are those where no party won a majority, or where the party with the most votes did not form the government.

Dashed line: 50% of votes cast. ◆ marks a hung parliament or an election where most votes and government formation diverged.

View as table
ElectionGovernment formed byTypeVote share
1945LabourSingle-party majority48.1%
1950LabourSingle-party majority46.1%
1951ConservativeSingle-party majority44.0%
1955ConservativeSingle-party majority49.6%
1959ConservativeSingle-party majority49.4%
1964LabourSingle-party majority44.1%
1966LabourSingle-party majority47.9%
1970ConservativeSingle-party majority46.4%
Feb 74LabourSingle-party minority37.1%
Oct 74LabourSingle-party majority39.3%
1979ConservativeSingle-party majority43.9%
1983ConservativeSingle-party majority42.4%
1987ConservativeSingle-party majority42.3%
1992ConservativeSingle-party majority41.9%
1997LabourSingle-party majority43.2%
2001LabourSingle-party majority40.7%
2005LabourSingle-party majority35.2%
2010Conservative–Liberal Democrat coalitionCoalition36.1%
2015ConservativeSingle-party majority36.8%
2017ConservativeMinority with confidence-and-supply42.3%
2019ConservativeSingle-party majority43.6%
2024LabourSingle-party majority33.7%

22 of the 22 postwar governments in this chart were formed on less than half the votes cast. Under a constituency-based plurality system that is the expected outcome rather than a failure of it.

The trade-off, stated as an open question

Supporters of the current system argue that decisive single-party government is worth a gap between vote shares and seat shares. Advocates of proportional systems argue the reverse. That is a judgement about what an electoral system is for, and it is not one this page can settle with data.

Last verified 16 August 2026. Data: House of Commons Library, General election results from 1918 to 2019 (CBP-8647); House of Commons Library, General election 2024 results (CBP-10009); government formation per election.

Safe seats and marginals

UK Facts analytical conventionMargin bands are defined by UK Facts, not by any official body
Every constituency in 2024 by winning margin, grouped by region

One cell per constituency, grouped by region and ordered by winning margin. This is a grid, not a map — cell position carries no geographic meaning.

South East (91 seats)

London (75 seats)

North West (73 seats)

East of England (61 seats)

South West (58 seats)

Scotland (57 seats)

West Midlands (57 seats)

Yorkshire and The Humber (54 seats)

East Midlands (47 seats)

Wales (32 seats)

North East (27 seats)

Northern Ireland (18 seats)

  • Ultra-safe
  • Safe
  • Competitive
  • Marginal
View as table
RegionUltra-safeSafeCompetitiveMarginalTotal
South East427372391
London3320121075
North West272317673
East of England115271861
South West217261358
Scotland42123957
West Midlands414251457
Yorkshire and The Humber72617454
East Midlands21126847
Wales4167532
North East3175227
Northern Ireland456318

Why this is a grid and not a map. The intended graphic was a hex cartogram, which shows urban seats at the same size as rural ones. Drawing one requires a licensed 650-constituency hex layout, which this site does not yet have — and approximating the positions by hand would place seats wrongly while looking authoritative. The grid carries the same information about how many seats are safe and where, and makes no geographic claim at all.

The question this raises, asked rather than answered

If most constituencies are decided by wide margins, campaigns have an incentive to concentrate effort on the minority of seats that could change hands. Whether that focuses politics on a small set of persuadable voters — and whether that is a flaw or simply how any constituency system works — is a judgement this page does not make.

Last verified 16 August 2026. Data: House of Commons Library, General election 2024 results (CBP-10009).

Tactical voting

Under First Past the Post, a voter whose first choice cannot realistically win their constituency faces a structural incentive: vote sincerely and risk helping the candidate they least want, or vote for the strongest challenger to that candidate instead. A sincerevote is for the voter’s actual first preference; a tactical vote is for a different candidate chosen to affect the outcome.

This incentive is a property of the system rather than a claim about it. Systems using ranked ballots — the Alternative Vote and the Single Transferable Vote — largely remove it, because a lower preference still counts if a first preference cannot win.

Why there is no percentage here

This page publishes no national tactical-voting figure. Ballots record a cross, not a motivation, so the quantity simply is not measured by any official source. Survey estimates exist, but they vary widely with question wording and rest on voters accurately reporting their own reasoning after the fact. Publishing a single number would give a spurious precision to something nobody has counted.

Coalition government

The most common argument against proportional systems in the UK is that they make single-party government rare and coalition government normal, and that coalitions are less stable and less accountable. The most common answer is that coalitions are the norm across most of western Europe without evident instability, and that they force parties to negotiate rather than govern on a minority of the vote.

Both are arguments, and this page does not adjudicate between them with a comparative dataset. Doing that honestly would mean comparing government duration and election frequency across countries whose constitutions, party systems and political cultures differ in ways that make simple causal attribution invalid — a country with frequent elections may have them for reasons that have nothing to do with its electoral system. Until a clean primary or peer-reviewed dataset can carry that comparison, the section stays qualitative rather than offering numbers that would imply more than they show.

What the UK’s own record shows is on this page already: of the postwar governments charted above, one was a formal coalition and two governed without a majority.

Sources and methodology

Gallagher Index

The least-squares index of disproportionality. For each party, take the difference between its vote share and its seat share in percentage points, square it, sum across parties, halve the total and take the square root: √(½ × Σ(Vi − Si)²). Higher values indicate a larger aggregate difference between vote shares and seat shares. It is not a measure of fairness, and its value depends on how finely parties are grouped — which is why every year in the series uses the same five groups.

Effective number of parties

The Laakso–Taagepera measure: 1 / Σ(si, where siis each party’s share expressed as a fraction. Computed on vote shares it gives the effective number of electoral parties; on seat shares, the effective number of parliamentary parties. In 2024 the effective number of electoral parties was 3.85 and the effective number of parliamentary parties was 2.22. The chart comparing the two is in the next release.

Party grouping and lineage

The 1918–2019 source supports five groups only, so the cross-era series uses those groups for every year including 2024. “Liberal” covers the Liberal Party, the SDP–Liberal Alliance and the Liberal Democrats, as the source combines them. UKIP, the Brexit Party and Reform UK are separate parties and are never merged into a single series here: before 2024 they sit inside “all other parties”, and in 2024 Reform UK is shown in its own right. Northern Ireland parties are inside “all other parties” before 2024 and listed individually for 2024.

What follows from that constraint. Cross-era measures — the seat bonus chart, the Gallagher Index and the effective number of parties — use the five-group basis for every year including 2024, so the series is internally consistent. Anything requiring full party detail is 2024-only: the case study, the votes-per-MP chart, the allocation comparison and the party-position tracker. That boundary is a property of the source data, not an editorial choice, and it is marked on each chart.

Seat allocation methods

Largest remainder, Hare quota — the default, because it is close to neutral between large and small parties: quota = totalVotes / totalSeats; seats = floor(votes / quota), remaining seats to the largest (votes mod quota). D’Hondtquotient = votes / (seatsWon + 1); highest quotient takes each successive seat; systematically favours larger parties, and is the method used for the Senedd from 2026. Sainte-Laguëquotient = votes / (2 × seatsWon + 1); highest quotient takes each successive seat; more favourable to small and medium parties. No method is described as “pure PR”: the method is always named on screen, because the choice of formula changes who wins seats.

Mixed-member top-up — every constituency winner keeps their seat, and top-up seats are awarded one at a time to whichever party is furthest below its proportional entitlement. The chamber size is not assumed: it is the smallest chamber in which no party is over-represented on national vote share. This model reuses the single First Past the Post vote for both the constituency and the list component, which no real mixed-member system does, and is labelled accordingly where it appears.

Votes that did not elect anyone

Two measures, kept separate. The primarymeasure is objective: for each constituency, valid votes minus the winning candidate’s votes, summed nationally. The secondary measure is a convention rather than an official category: votes received by winning candidates beyond the number needed to exceed the runner-up. The two are never added together into a headline figure without being labelled a UK Facts analytical measure.

Safe-seat margin bands

Ultra-safe is a winning margin above 30 percentage points, safe 15–30, competitive 5–15 and marginal below 5. These bands are a UK Facts convention, not an official classification, and are labelled as such wherever they appear. “Electorate” means registered electors, not residents.

Boundaries and comparability

The 2024 election used new constituency boundaries. National vote and seat shares are unaffected by that, and no constituency-level comparison across 2024 is made anywhere on this page.

Government formation

Government type is recorded per election as one of: single-party majority, single-party minority, coalition, or minority with confidence-and-supply. It is not derived from seat counts, because the party with the most seats has not always formed the government and in two postwar elections the party with the most votes did not either.

Computed claims

Every statistic quoted in prose on this page is defined once as a computed claim — an identifier, the inputs it reads, the calculation, and the dataset it comes from — and read from there by the copy, the charts and the tables alike. There are currently 10 such claims on this page. No figure is typed into a component by hand, so the prose and the graphics cannot drift apart.

Licensing. Contains Parliamentary information licensed under the Open Parliament Licence v3.0. Electoral Commission material is used with attribution.

Every source used on this page

Datasets generated 2026-08-16 from the official published election results.

Beyond the voting system

How votes become seats is one part of how Britain is governed. These sections are in build and will link from here when they publish.

  • In build

    The House of Lords

    An appointed second chamber, its composition, and what reform proposals would change.

  • In build

    Devolution

    What Scotland, Wales, Northern Ireland and English mayors actually decide.

  • In build

    Executive power

    Prerogative powers, secondary legislation and what Parliament does not vote on.

  • In build

    The uncodified constitution

    Where Britain’s rules are written down, and where they are convention.

This page is the third part of a sequence on how power is exercised in Britain: who owns the media and who funds the parties shape the argument voters hear; this page covers how their votes become seats. See also national polling and the referendum that a different voting rule decided.