The calculated distance (air line) between Bochum-Hordel and Kalmthout is approximately 117 miles respectively 188 kilometers.
By car or train, the actual journey to Kalmthout is certainly longer, as only the direct route (as the crow flies) between Bochum-Hordel and Kalmthout has been calculated here.
Air line (approximately)
188 kilometers
101 nautical miles