The calculated distance (air line) between Udon Thani and Sakon Nakhon is approximately 92 miles respectively 147 kilometers.
By car or train, the actual journey to Sakon Nakhon is certainly longer, as only the direct route (as the crow flies) between Udon Thani and Sakon Nakhon has been calculated here.
Air line (approximately)
147 kilometers
79 nautical miles