The number of seats in the regional Assembly was determined by the population count, with 1 seat per each 50,000 inhabitants or fraction greater than 25,000, according to the most updated census data. As the updated population census for the 2011 election was the corresponding to year 2010 (6,458,684), the Assembly size was set to 129 seats.
Poll results are listed in the table below in reverse chronological order, showing the most recent first. The highest percentage figure in each polling survey is displayed in bold, and the background shaded in the leading party's colour. In the instance that there is a tie, then no figure is shaded. The lead column on the right shows the percentage-point difference between the two parties with the highest figures. Poll results use the date the survey's fieldwork was done, as opposed to the date of publication. However, if such date is unknown, the date of publication will be given instead.
Opinion polls showing seat projections are displayed in the table below. The highest seat figures in each polling survey have their background shaded in the leading party's colour. In the instance that there is a tie, then no figure is shaded. 65 seats were required for an absolute majority in the Madrid Assembly.
65 seats needed for majority (01/01/2010–22/05/2011)
61 seats needed for majority (27/05/2007–01/01/2010)
^ abThis survey shows its poll results projected over candidacy votes (that is, votes going for political parties, excluding blank ballots). The vote percentage in the official election is calculated including blank ballots into the estimation. In order to obtain data comparable to both the official results as well as those of other surveys, a rule of three has been applied to the survey projections, with the results of the calculation being shown instead.