The 2018 Swedish general election, scheduled for Sunday 9 September 2018, will elect the members of the Riksdag which in turn will elect a prime minister.
The Swedish Riksdag is made up of 349 MPs, and all are elected through proportional representation on multi-member party lists that are either regional (most major parties) or national (Sweden Democrats). Each of the 29 constituencies has a set number of parliamentarians that is divided through constituency results to ensure regional representation. The other MPs are then elected through a proportional balancing, to ensure that the numbers of elected MPs for the various parties accurately represent the votes of the electorate. The Swedish constitution (Regeringsformen) 1 Ch. 4 § says that the Riksdag is responsible for taxation and making laws, and 1 Ch. 6 § says that the government is held responsible to the Riksdag. This means that Sweden has parliamentarism in a constitutional monarchy—ensuring that the government is appointed by the people’s representatives; the Prime Minister is therefore indirectly elected. A minimum of 4% of the national vote is required for a party to enter the Riksdag, alternatively 12% or more within a constituency.
Sources and Further Reading:
6 European elections to watch this year
How to vote in the 2018 Swedish election
Swedish general election, 2018