The calculated distance (air line) between Sint-Pieters-Leeuw and Dendermonde is approximately 18 miles respectively 29 kilometers.
By car or train, the actual journey to Dendermonde is certainly longer, as only the direct route (as the crow flies) between Sint-Pieters-Leeuw and Dendermonde has been calculated here.
Air line (approximately)
29 kilometers
16 nautical miles