The calculated distance (air line) between Jisr ash Shughūr and Dūmā is approximately 155 miles respectively 249 kilometers.
By car or train, the actual journey to Dūmā is certainly longer, as only the direct route (as the crow flies) between Jisr ash Shughūr and Dūmā has been calculated here.
Air line (approximately)
249 kilometers
135 nautical miles