The calculated distance (air line) between Sant Cugat del Vallès and Viladecans is approximately 11 miles respectively 18 kilometers.
By car or train, the actual journey to Viladecans is certainly longer, as only the direct route (as the crow flies) between Sant Cugat del Vallès and Viladecans has been calculated here.
Air line (approximately)
18 kilometers
10 nautical miles