Strategic Voting in Spain: D'Hondt Math to Oust Sánchez

The D'Hondt method does not apply a single threshold across Spain; effective cutoffs range from 15-20% in provinces with 1-5 seats to near-proportional representation in those with 11 or more. Consequently, voting for Vox in small districts often results in a seat for the PSOE, whereas in large districts it has no impact on distribution.

The D'Hondt law is not a uniform rule applied equally throughout Spain. It is a seat allocation method combined with the size of each constituency, and that size changes everything. In a province electing 3 deputies, the system behaves almost like a disguised majoritarian one. In one electing 32, it closely resembles pure proportionality. Understanding this difference separates a counted vote from a wasted one.

## Why a 3-seat province differs from a 32-seat one

The number of seats per constituency determines the actual percentage of votes needed to secure a deputy. It is not the 3% fixed by general electoral law: that is a legal minimum that rarely decides outcomes. The effective threshold is set by arithmetic. In a 3-seat province, the last deputy goes to whoever exceeds approximately 20% of valid votes. In a 5-seat one, this cutoff drops toward 16%-18%. In an 8-seat one, it hovers around 10%-12%. And in **Madrid**, with **37 seats**, or **Barcelona**, with **32**, the cutoff plummets to 3%-4%.

This means a party with 10% of the vote in **Soria** (2 seats) gets nothing, while that same 10% in **Valencia** (16 seats) translates into one or two deputies. Fragmentation is not penalized equally everywhere. In small provinces, splitting the vote between two parties of the same bloc can hand the last seat to the rival party by a margin of a few thousand votes.

The practical consequence is that tactical voting advice cannot be national. It depends on where you vote. In **Ávila** (3 seats), the threshold exceeds 18% and Vox fails to win a deputy. In **Segovia** (3 seats), that threshold is unreachable for Vox barring a historic shift. In **Teruel** (3 seats), competition with other formations makes concentrating the vote on the PP the only way to contest the seat. Conversely, in **Almería** (6 seats), Vox has a floor above 20% and secures a direct seat.

## Where voting for Vox wins seats without loss

There is a group of constituencies where proportionality is high enough that voting for either right-wing party translates into seats without leakage. In **Alicante** (12 seats), **Málaga** (11), **Sevilla** (12), **Murcia** (10), **Barcelona** (32), **Madrid** (37), and **Valencia** (16), both parties gain representation without division benefiting the PSOE. These are provinces where free voting is mathematically rational.

There are also medium-sized constituencies where Vox clears the threshold comfortably. **Cádiz** (9 seats), **Granada** (7), **Asturias** (7), **Toledo** (6), **Córdoba** (6), **Zaragoza** (7), **Illes Balears** (8), **Las Palmas** (8), **S.C. Tenerife** (7), and **Pontevedra** (7) allow both parties to win deputies without risking the last seat due to fragmentation. In **Almería** (6 seats), Vox has a very high floor, above 20%, and secures a direct seat.

The Galician case deserves a separate paragraph. In **A Coruña** (8 seats), **Pontevedra** (7), **Lugo** (4), and **Ourense** (4), Vox's floor is low and votes for Vox result in no seat. It neither subtracts from the PSOE nor BNG, but does not add to the bloc either. In **Bizkaia** (8 seats) and **Gipuzkoa** (6), Vox fails to reach the threshold and only the PP has mathematical options. In **Álava** (4 seats), the PP contests the last seat against nationalism and Vox misses the cutoff.

## Province-by-province list: where to concentrate and where to split

The technical recommendation derived from mathematical analysis divides into two blocks. In small provinces, concentrating the vote on the PP maximizes bloc seats. In large ones, the vote splits without cost. The boundary lies around 6-8 seats, where the threshold drops below 14% and Vox begins to have real options.

Provinces where the recommendation is to vote for the PP: **A Coruña**, **Álava**, **Albacete**, **Ávila**, **Badajoz**, **Bizkaia**, **Burgos**, **Cáceres**, **Cantabria**, **Castellón**, **Ceuta**, **Ciudad Real**, **Cuenca**, **Gipuzkoa**, **Girona**, **Guadalajara**, **Huelva**, **Huesca**, **Jaén**, **La Rioja**, **León**, **Lleida**, **Lugo**, **Melilla**, **Navarra**, **Ourense**, **Palencia**, **Pontevedra**, **Salamanca**, **Segovia**, **Soria**, **Tarragona**, **Teruel**, **Valladolid**, **Zamora**. In **Ceuta** and **Melilla**, with 1 seat each, the district is single-member: the winner takes all, and splitting favors the PSOE or Coalición por Melilla.

Provinces where the recommendation is to vote for PP or Vox indistinctly: **Alicante**, **Almería**, **Asturias**, **Barcelona**, **Cádiz**, **Córdoba**, **Granada**, **Illes Balears**, **Las Palmas**, **Madrid**, **Málaga**, **Murcia**, **S.C. Tenerife**, **Sevilla**, **Toledo**, **Valencia**, **Zaragoza**. In **Murcia** (10 seats), both parties capitalize their votes at 100%. In **Toledo** (6 seats), Vox ensures representation without harming the bloc.

The case of **Soria** (2 seats) is the most extreme: it ends up 1-1 or 2-0, and voting for a third party guarantees a deputy to the PSOE. In **Palencia** (3 seats), **Zamora** (3), **Cuenca** (3), **Guadalajara** (3), and **Segovia** (3), votes for a third party are lost regarding seat allocation. In **Burgos** (4 seats), the threshold is very high and division hands the second seat to the PSOE. In **Salamanca** (4), concentration guarantees a 3-1 outcome versus 2-2. In **Lleida** (4), Vox misses the cutoff and concentrating on the PP is the only path.

## What arithmetic says about tactical voting

The conclusion drawn from the analysis is that tactical voting is not a national slogan, but a decision dependent on the province. In constituencies with 1 to 5 seats, the real 15%-20% threshold turns a vote for a third party into a wasted vote that benefits the PSOE. In those with 11 or more, near-pure proportionality makes voting for PP or Vox indifferent to the final distribution.

This does not miccionan the system is unjust by design. It means the D'Hondt law, combined with provincial seat distribution, favors large parties in small provinces and allows fragmentation in large ones. Any voting strategy ignoring this difference operates with an incomplete picture. Mathematics does not decide elections, but it decides how many votes are needed for each seat. And that changes depending on where the vote is cast.