The calculated distance (air line) between L'Hospitalet de Llobregat and Terrassa is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Terrassa is certainly longer, as only the direct route (as the crow flies) between L'Hospitalet de Llobregat and Terrassa has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles