The calculated distance (air line) between Taphan Hin and Udon Thani is approximately 177 miles respectively 285 kilometers.
By car or train, the actual journey to Udon Thani is certainly longer, as only the direct route (as the crow flies) between Taphan Hin and Udon Thani has been calculated here.
Air line (approximately)
285 kilometers
154 nautical miles