The calculated distance (air line) between Sint-Pieters-Leeuw and Turnhout is approximately 48 miles respectively 78 kilometers.
By car or train, the actual journey to Turnhout is certainly longer, as only the direct route (as the crow flies) between Sint-Pieters-Leeuw and Turnhout has been calculated here.
Air line (approximately)
78 kilometers
42 nautical miles