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