The calculated distance (air line) between Bad Lauterberg im Harz and Duisburg is approximately 160 miles respectively 257 kilometers.
By car or train, the actual journey to Duisburg is certainly longer, as only the direct route (as the crow flies) between Bad Lauterberg im Harz and Duisburg has been calculated here.
Air line (approximately)
257 kilometers
139 nautical miles