The calculated distance (air line) between Stung Treng and Ubon Ratchathani is approximately 140 miles respectively 225 kilometers.
By car or train, the actual journey to Ubon Ratchathani is certainly longer, as only the direct route (as the crow flies) between Stung Treng and Ubon Ratchathani has been calculated here.
Air line (approximately)
225 kilometers
122 nautical miles