The calculated distance (air line) between Watermael-Boitsfort and Merksem is approximately 31 miles respectively 50 kilometers.
By car or train, the actual journey to Merksem is certainly longer, as only the direct route (as the crow flies) between Watermael-Boitsfort and Merksem has been calculated here.
Air line (approximately)
50 kilometers
27 nautical miles