The calculated distance (air line) between Düsseldorf and Knokke-Heist is approximately 152 miles respectively 244 kilometers.
By car or train, the actual journey to Knokke-Heist is certainly longer, as only the direct route (as the crow flies) between Düsseldorf and Knokke-Heist has been calculated here.
Air line (approximately)
244 kilometers
132 nautical miles