The calculated distance (air line) between Najaf and Ash Shāmīyah is approximately 16 miles respectively 25 kilometers.
By car or train, the actual journey to Ash Shāmīyah is certainly longer, as only the direct route (as the crow flies) between Najaf and Ash Shāmīyah has been calculated here.
Air line (approximately)
25 kilometers
14 nautical miles