Swing simulator
A swing of a few points often decides a state election. Move vote share from one party to another and see which seats would have changed hands.
How this works: the simulator uses each seat's winner and runner-up. Where one of your two parties finished in the top two, it moves the chosen points of vote share between them and checks whether the lead changes. Seats where neither party finished in the top two stay as they were. This is a uniform swing model, the standard first estimate, not a forecast. The line chart repeats the same calculation at every swing from 0 to 15 points.
Source: Election Commission of India results, 2009 onwards.