Scottish Parliament Seat Calculator

The Scottish Parliament uses the Additional Member System (AMS). Voters cast two votes: one for a constituency candidate (first-past-the-post) and one for a regional party list.

There are 73 constituency seats and 56 regional list seats, for a total of 129 MSPs. A party needs 65 seats for a majority.

Scotland is divided into 8 regions, each electing 7 regional MSPs using the D'Hondt method. The D'Hondt formula divides each party's regional vote by the number of seats they've already won (constituency + regional + 1), which compensates for parties that dominate constituency seats and makes the overall result more proportional.

The calculator applies differential swing to baseline results. When you enter polling numbers, the model calculates how much each party's vote has changed nationally and applies that swing to each constituency, adjusted for local conditions.

Constituencies where a party is already strong see slightly different swing effects than seats where they are weak. This produces more realistic results than simple uniform swing, which assumes every seat moves by the same amount.

For the regional list, the same approach is applied to each region's vote totals, then D'Hondt allocation determines which parties win the 7 list seats per region.

The 2026 election uses new constituency and regional boundaries set by Boundaries Scotland. While there are still 73 constituencies and 8 regions, around 21 seats have changed shape or name, and two regions have been renamed.

Since the 2021 election was fought on different boundaries, we use notional results to estimate how each new seat would have voted in 2021. This is done using population data from Boundaries Scotland, which tells us what share of each new constituency came from each old one.

Projections use 2021 Holyrood election results, adjusted to the new 2026 boundaries using Boundaries Scotland population data. On the new boundaries, the notional 2021 result gives SNP 64, Conservative 31, Labour 22, Green 8, and Liberal Democrat 4 total seats (73 constituency + 56 regional list).

The model does not account for local factors, tactical voting, or candidate popularity. The notional baseline assumes voters within each old constituency behaved uniformly, which may not fully capture neighbourhood-level differences. Regional list seat allocation assumes the input vote shares apply evenly across all regions.