The calculated distance (air line) between San Sebastián de los Reyes and San Fernando de Henares is approximately 10 miles respectively 17 kilometers.
By car or train, the actual journey to San Fernando de Henares is certainly longer, as only the direct route (as the crow flies) between San Sebastián de los Reyes and San Fernando de Henares has been calculated here.
Air line (approximately)
17 kilometers
9 nautical miles