The calculated distance (air line) between Mukdahan and Ubon Ratchathani is approximately 91 miles respectively 146 kilometers.
By car or train, the actual journey to Ubon Ratchathani is certainly longer, as only the direct route (as the crow flies) between Mukdahan and Ubon Ratchathani has been calculated here.
Air line (approximately)
146 kilometers
79 nautical miles