The city's total land area is roughly . Its greatest east-west span is about , and its greatest north-south span is about . City limits are long. Siegen lies at a median elevation of above sea level. The city's greatest elevation is the peak of the Pfannenberg at above sea level at southern city limits. Siegen's lowest point is above sea level at Niederschelden at southwestern city limits, which there also forms the state boundary with Rhineland-Palatinate. Roughly 60% of the city's land is wooded, making Siegen one of Germany's greenest cities.