The calculated distance (air line) between Castrop-Rauxel and Lüdinghausen is approximately 16 miles respectively 25 kilometers.
By car or train, the actual journey to Lüdinghausen is certainly longer, as only the direct route (as the crow flies) between Castrop-Rauxel and Lüdinghausen has been calculated here.
Air line (approximately)
25 kilometers
14 nautical miles