The calculated distance (air line) between Ubon Ratchathani and Khon Kaen is approximately 158 miles respectively 254 kilometers.
By car or train, the actual journey to Khon Kaen is certainly longer, as only the direct route (as the crow flies) between Ubon Ratchathani and Khon Kaen has been calculated here.
Air line (approximately)
254 kilometers
137 nautical miles