The calculated distance (air line) between Sint-Gillis-Waas and Uccle is approximately 30 miles respectively 49 kilometers.
By car or train, the actual journey to Uccle is certainly longer, as only the direct route (as the crow flies) between Sint-Gillis-Waas and Uccle has been calculated here.
Air line (approximately)
49 kilometers
26 nautical miles