The calculated distance (air line) between Watermael-Boitsfort and Turnhout is approximately 43 miles respectively 69 kilometers.
By car or train, the actual journey to Turnhout is certainly longer, as only the direct route (as the crow flies) between Watermael-Boitsfort and Turnhout has been calculated here.
Air line (approximately)
69 kilometers
37 nautical miles