The calculated distance (air line) between Argentona and L'Hospitalet de Llobregat is approximately 21 miles respectively 33 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 Argentona and L'Hospitalet de Llobregat has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles