The calculated distance (air line) between Berchem-Sainte-Agathe and Leuven is approximately 18 miles respectively 28 kilometers.
By car or train, the actual journey to Leuven is certainly longer, as only the direct route (as the crow flies) between Berchem-Sainte-Agathe and Leuven has been calculated here.
Air line (approximately)
28 kilometers
15 nautical miles