The calculated distance (air line) between Düsseldorf and Mönchengladbach is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Mönchengladbach is certainly longer, as only the direct route (as the crow flies) between Düsseldorf and Mönchengladbach has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles