The calculated distance (air line) between Kelkheim-Mitte and Gelsenkirchen is approximately 112 miles respectively 180 kilometers.
By car or train, the actual journey to Gelsenkirchen is certainly longer, as only the direct route (as the crow flies) between Kelkheim-Mitte and Gelsenkirchen has been calculated here.
Air line (approximately)
180 kilometers
97 nautical miles