The calculated distance (air line) between L'Hospitalet de Llobregat and Sant Martí is approximately 7 miles respectively 11 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'Hospitalet de Llobregat and Sant Martí has been calculated here.
Air line (approximately)
11 kilometers
6 nautical miles