The calculated distance (air line) between L'Ametlla del Vallès and Sant Martí is approximately 18 miles respectively 28 kilometers.
By car or train, the actual journey to Sant Martí is certainly longer, as only the direct route (as the crow flies) between L'Ametlla del Vallès and Sant Martí has been calculated here.
Air line (approximately)
28 kilometers
15 nautical miles