The calculated distance (air line) between Ath Thumāmah Sittah wa Arba‘ūn and Dukhān is approximately 49 miles respectively 79 kilometers.
By car or train, the actual journey to Dukhān is certainly longer, as only the direct route (as the crow flies) between Ath Thumāmah Sittah wa Arba‘ūn and Dukhān has been calculated here.
Air line (approximately)
79 kilometers
43 nautical miles