The calculated distance (air line) between Dūmā and Khān Shaykhūn is approximately 130 miles respectively 209 kilometers.
By car or train, the actual journey to Khān Shaykhūn is certainly longer, as only the direct route (as the crow flies) between Dūmā and Khān Shaykhūn has been calculated here.
Air line (approximately)
209 kilometers
113 nautical miles