The calculated distance (air line) between Alcalá de Henares and Barajas de Madrid is approximately 11 miles respectively 18 kilometers.
By car or train, the actual journey to Barajas de Madrid is certainly longer, as only the direct route (as the crow flies) between Alcalá de Henares and Barajas de Madrid has been calculated here.
Air line (approximately)
18 kilometers
10 nautical miles