Parliamentary Coalition & Seat Allocator
When election exit polls reveal deep shifts—like sudden surges or collapsing incumbents—majority math decides who can actually govern. Calculate Sainte-Laguë or D'Hondt seat allocation, enforce 5% threshold cutoffs, and test cordon sanitaire coalition viability.
Parliamentary Hemicycle
120 Seats • Absolute Majority: 61 SeatsUnderstanding Coalition Math in Fragmented Democracies
When single-party majorities disappear and polarized or radical parties surge past 25% or 30%, conventional post-war two-party alliances (like CDU + FDP or SPD + Greens) can no longer reach the required 50% + 1 seat threshold.
If major centrist parties maintain a cordon sanitaire (firewall) refusing to govern with far-right or populist extremes, governing requires unwieldy 3-way or 4-way alliances (such as "Kenya" CDU+SPD+Greens or "Zimbabwe" coalitions), raising cabinet instability and policy veto gridlock.
Frequently Asked Questions
How does the 5% threshold affect seat distribution?
In systems like Germany or New Zealand, parties receiving less than the threshold (typically 5% of party list votes) receive zero seats (unless winning direct constituency mandates). The remaining valid seats are redistributed solely among the qualifying parties, meaning a coalition can win an absolute majority of parliament seats with significantly less than 50% of the total raw vote.
Why Sainte-Laguë / Webster vs. D'Hondt?
The Sainte-Laguë (Webster) method uses odd divisors (1, 3, 5, 7...) and is mathematically unbiased between small and large parties. The D'Hondt method uses linear integer divisors (1, 2, 3, 4...) and slightly favors larger parties, occasionally nudging larger parties into narrow single-party majorities.
What is the Laakso-Taagepera ENP index?
The Effective Number of Parliamentary Parties ($N = 1 / \sum s_i^2$) quantifies political fragmentation. An ENP above 4.5 indicates high fragmentation requiring complex multiparty negotiations.