Political knowledge is one of the most important constructs for political behavior research, although scholars often ignore how general knowledge translates into specific information that citizens use to evaluate the party supply. This task is even more complex in multi-party systems. We analyze the accuracy of voters’ party placements benchmarked to expert placements in 24 European multi-party systems focusing on the role of general political knowledge given party system characteristics. Our results indicate that while more knowledgeable voters view the party system more similarly to experts, this difference is substantially smaller in ideologically polarized party systems. Thus, the required general political knowledge for an accurate ordering of parties on the left–right scale is much lower in polarized party systems. Our findings have important implications for our understanding of how competition can fulfill its function of linking citizens and political elites at the moment of democratic elections.