The calculated distance (air line) between Gelsenkirchen and Mönchengladbach is approximately 36 miles respectively 58 kilometers.
By car or train, the actual journey to Mönchengladbach is certainly longer, as only the direct route (as the crow flies) between Gelsenkirchen and Mönchengladbach has been calculated here.
Air line (approximately)
58 kilometers
31 nautical miles