The calculated distance (air line) between Alcalá de Henares and Alcobendas is approximately 15 miles respectively 25 kilometers.
By car or train, the actual journey to Alcobendas is certainly longer, as only the direct route (as the crow flies) between Alcalá de Henares and Alcobendas has been calculated here.
Air line (approximately)
25 kilometers
13 nautical miles