To govern Barcelona, ​​it will be essential to forge alliances and it is quite probable that the sum of two political formations will not be enough to reach an absolute majority, which in the City Council of the Catalan capital is fixed at 21 of the 41 councilors that the people of Barcelona will elect next 28 of May. La Vanguardia and Public Affairs Experts make an interactive pactometer available to users of this newspaper’s website that allows them to forecast the outcome of the next elections and, based on them, establish the sums in order to define possible government pacts.