The calculated distance (air line) between Rong Kwang and Udon Thani is approximately 174 miles respectively 281 kilometers.
By car or train, the actual journey to Udon Thani is certainly longer, as only the direct route (as the crow flies) between Rong Kwang and Udon Thani has been calculated here.
Air line (approximately)
281 kilometers
151 nautical miles