Elmshorn is a town in the district of Pinneberg in Schleswig-Holstein in Germany. It is 30 km north of Hamburg on the small river Krückau, a tributary of the Elbe, and with about 50,000 inhabitants is the sixth-largest town in the state of Schleswig-Holstein, Germany. It is the birthplace of writer and editor Hermann Schlüter (1851–1919), the mathematician Hermann Weyl (1885–1955) and the medievalist Heinz Woehlk.