The calculated distance (air line) between Udon Thani and Khon Kaen is approximately 67 miles respectively 108 kilometers.
By car or train, the actual journey to Khon Kaen is certainly longer, as only the direct route (as the crow flies) between Udon Thani and Khon Kaen has been calculated here.
Air line (approximately)
108 kilometers
58 nautical miles