How UK general elections work

The House of Commons has 650 seats, one for each constituency. At a general election every constituency elects one MP using first past the post: the candidate with the most votes wins, even without a majority of votes.

Forming a government

The party that can command the confidence of the House of Commons forms the government, and its leader becomes prime minister. In practice a party needs 326 seats for an overall majority (fewer if the Speaker and Sinn Féin MPs, who do not take their seats, are discounted). When no party has a majority the result is a hung parliament, which can lead to a minority government, a confidence-and-supply agreement or a coalition, as in 2010.

When elections happen

A Parliament lasts at most five years from the day it first meets. The prime minister can ask the monarch to dissolve Parliament earlier. Polling day is usually a Thursday.

By-elections

When a seat falls vacant between general elections, because an MP dies, resigns, is recalled or is disqualified, a by-election is held in that constituency only.

Who can vote

British, Irish and qualifying Commonwealth citizens who are registered to vote and meet the minimum voting age (18 for UK general elections at the time of writing). At UK general elections voters need photo identification at polling stations (in Great Britain since 2024; in Northern Ireland since 2003).

Try the swing calculator · How votes turn into seats · Hung parliaments