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Swing calculator: change the vote, see the seats

Move each party's share of the vote in Great Britain and see which constituencies change hands under uniform national swing, starting from the 2024 or 2019 result.

Change in Great Britain vote share

Each slider adds (or removes) points to that party in every seat in England, Scotland and Wales; the "Others" share absorbs the difference so shares still add up. Northern Ireland seats keep their actual result.

Uniform national swing is a simple model, not a forecast: real swings vary from seat to seat. Base data: 2024 and 2019 constituency results (2019 Brexit Party votes are treated as Reform UK). Methodology