The calculated distance (air line) between Alella and L'Hospitalet de Llobregat is approximately 14 miles respectively 22 kilometers.
By car or train, the actual journey to L'Hospitalet de Llobregat is certainly longer, as only the direct route (as the crow flies) between Alella and L'Hospitalet de Llobregat has been calculated here.
Air line (approximately)
22 kilometers
12 nautical miles