The calculated distance (air line) between Dukhān and Az̧ Z̧a‘āyin is approximately 45 miles respectively 72 kilometers.
By car or train, the actual journey to Az̧ Z̧a‘āyin is certainly longer, as only the direct route (as the crow flies) between Dukhān and Az̧ Z̧a‘āyin has been calculated here.
Air line (approximately)
72 kilometers
39 nautical miles