MaktkartanPublished: Text updated:
The problem they solve
If all 349 seats were allocated within the 29 constituencies alone, the result would be skewed. In a small constituency with eight seats it takes over twelve percent of the vote to win a single seat - votes for smaller parties are lost. The sum of 29 such rounding effects systematically favours parties with concentrated support and penalises parties whose voters are evenly spread.
The adjustment seats are the correction. The constitution therefore splits the Riksdag's seats into 310 fixed constituency seats and 39 adjustment seats. The point is that the final composition of the chamber should match each party's share of the nationwide vote, not the sum of 29 separate elections.
How they are calculated, step by step
Step 1: only parties with at least 4 percent of the nationwide vote take part. Step 2: the 310 fixed seats are allocated within each constituency using the adjusted odd-number method (Sainte-Laguë), where the first comparison figure is the vote total divided by 1.4 and then by 3, 5, 7 and so on - the high first divisor dampens the advantage for the very smallest parties.
Step 3: the whole country is treated as a single constituency and all 349 seats are allocated nationally with the same method. That gives each party its fair total. Step 4: for every party the national figure is compared with the fixed seats it already won. The difference is filled with adjustment seats, until all 39 have been handed out.
Step 5: each adjustment seat is placed in the constituency where the party has its highest unused comparison figure - that is, where it came closest to winning another fixed seat. This is why a member can be elected on an adjustment seat in a constituency where the party is otherwise weak.
A party that has won more fixed seats than the national allocation gives keeps them - seats are never taken away. Instead the adjustment seats are redistributed among the other parties, which in practice makes the correction slightly less exact.
The 2026 election as an example
After the election of 13 September 2026 the eight parliamentary parties together received 6 660 230 valid votes out of 6 767 429. Each party's final seat figure - S 99, M 70, SD 62, V 30, C 25, MP 22, KD 22, L 19 - is the result of the national allocation of all 349 seats, not of 29 separate calculations.
On the constituency map you can see how many seats each constituency has and how the parties did there. Compare a party's share in a constituency with the seats it took: the gap between those two numbers is exactly what the adjustment seats exist to even out nationally.
The exception: the twelve-percent rule
A party that fails to reach 4 percent nationally but wins at least 12 percent in a single constituency may still take part in allocating that constituency's fixed seats. Such parties never take part in the adjustment seats, however. The rule has never actually produced a seat, but it remains in the Elections Act.