The calculated distance (air line) between Saint-Josse-ten-Noode and Leuven is approximately 14 miles respectively 23 kilometers.
By car or train, the actual journey to Leuven is certainly longer, as only the direct route (as the crow flies) between Saint-Josse-ten-Noode and Leuven has been calculated here.
Air line (approximately)
23 kilometers
13 nautical miles