The calculated distance (air line) between Dortmund and Oud-Turnhout is approximately 108 miles respectively 173 kilometers.
By car or train, the actual journey to Oud-Turnhout is certainly longer, as only the direct route (as the crow flies) between Dortmund and Oud-Turnhout has been calculated here.
Air line (approximately)
173 kilometers
94 nautical miles