What a vote was worth in 2023: from Soria to Madrid, a 3.7-fold gap

On the electoral roll and seat allocation for the 2023 general election, according to data from the Ministerio del Interior, each seat in Soria corresponded to 37,884 registered voters and each seat in Madrid to 141,204. Put another way, behind a deputy from Madrid stood 3.7 times as many voters as behind one from Soria. This is neither a miscalculation nor a statistical oddity: it is what happens when the Congreso is shared out province by province.

With 54 days to go until the general election of 29 November 2026, the map left by 2023 is worth revisiting. It explains a good deal about how votes become seats, and why the count of ballots and the count of deputies do not always tell the same story.

From a seat in Teruel to a seat in Madrid

In 2023 the total electoral roll stood at 37,469,458 voters, including those resident abroad, and the average was 107,056 voters per seat, according to Su Momento's calculation using Interior data. But the average, as is so often the case, describes almost nobody. At the bottom end was Teruel, with 106,352 voters and 3 seats: 35,451 voters for each.

After Teruel came Soria, with 37,884 voters per seat; Segovia, with 39,818; Ávila, with 45,556; and Palencia, with 45,881, all on the official 2023 figures. At the other end, Madrid, with 5,224,561 voters and 37 seats, was the province with the most voters per deputy. It was joined by Asturias (137,003), A Coruña (135,709), Barcelona (132,609) and Sevilla (130,340). The chart shows the two ends of that ladder.

Why the system draws it this way

The key lies in the constituency. Deputies are not drawn from one large national pool but from each province separately, and each elects its own number of seats. That number rises with population, but not at the same pace: on the 2023 figures, Soria, with 75,768 voters, elected 2 deputies, and Madrid, with 5,224,561, elected 37.

The effect is that less populous provinces carry more relative weight in the Congreso than their electoral roll alone would warrant, and the most populous ones less. It is a design choice with both defenders and critics, and here it is merely described. If you would like to see how voting works step by step, you can read how to vote, and compare the profiles of Soria and Madrid.

How many votes each seat cost

The other side of this allocation shows up in the parties. According to the final 2023 results, the PP gathered 8,160,837 votes and 137 seats, a rate of 59,568 votes per seat, and the PSOE won 7,821,718 votes and 121 seats, at 64,642 votes per seat. Vox obtained 3,057,000 votes and 33 seats, at 92,636 per seat, and Sumar 3,044,996 votes and 31 seats, at 98,226 per seat.

Among the regionally based candidacies, the 2023 figures were 55,458 votes per seat for the PNV, 55,855 for EH Bildu, 56,490 for Junts and 66,574 for ERC. UPN, with 52,188 votes, secured the cheapest seat in the table. At the opposite end, CC needed 116,363 votes for its seat and the BNG 153,995.

These differences depend not only on how many votes each party gathers but on where it gets them. Votes concentrated in provinces where a candidacy is in contention for seats turn into deputies more efficiently; those spread across constituencies where they fall short of a seat remain, so to speak, on the meter without ever reaching the till. And winning a seat in a province with few voters per deputy takes fewer votes than winning one in a province with many.

That is why two parties with a similar number of votes can end up with different numbers of seats, and why the national figures tell only half the story. The other half is written province by province. To find out how many voters stood behind each seat in your constituency, you can check your province before 29 November.