The calculated distance (air line) between Chon Daen and Udon Thani is approximately 153 miles respectively 246 kilometers.
By car or train, the actual journey to Udon Thani is certainly longer, as only the direct route (as the crow flies) between Chon Daen and Udon Thani has been calculated here.
Air line (approximately)
246 kilometers
133 nautical miles