The calculated distance (air line) between Bad Sooden-Allendorf and Duisburg is approximately 139 miles respectively 224 kilometers.
By car or train, the actual journey to Duisburg is certainly longer, as only the direct route (as the crow flies) between Bad Sooden-Allendorf and Duisburg has been calculated here.
Air line (approximately)
224 kilometers
121 nautical miles