The calculated distance (air line) between Louvain-la-Neuve and Ixelles is approximately 16 miles respectively 25 kilometers.
By car or train, the actual journey to Ixelles is certainly longer, as only the direct route (as the crow flies) between Louvain-la-Neuve and Ixelles has been calculated here.
Air line (approximately)
25 kilometers
14 nautical miles