The calculated distance (air line) between Duisburg and Marburg an der Lahn is approximately 97 miles respectively 156 kilometers.
By car or train, the actual journey to Marburg an der Lahn is certainly longer, as only the direct route (as the crow flies) between Duisburg and Marburg an der Lahn has been calculated here.
Air line (approximately)
156 kilometers
84 nautical miles