In the Bundestag election, all people who are over 18 years old and have German citizenship can vote.
In the State elections (“Landtagswahlen”), all people who are over 18 years old and have German citizenship can vote. In Brandenburg, Schleswig-Holstein, Bremen and Hamburg, you can vote from the age of 16- German citizenship remains a requirement.
All German citizens and EU citizens who have lived in Germany for more than three months can vote in the municipal/ local elections (“Kommunalwahlen”). The minimum age depends on the state. In Saxony, Saarland, Rhineland-Palatinate, Hesse and Bavaria, only people aged 18 and over are allowed to vote. In other federal states, you can vote in local elections from the age of 16.
Furthermore, all adult EU citizens are allowed to vote in the European elections.