The calculated distance (air line) between Si Bun Rueang and Udon Thani is approximately 46 miles respectively 74 kilometers.
By car or train, the actual journey to Udon Thani is certainly longer, as only the direct route (as the crow flies) between Si Bun Rueang and Udon Thani has been calculated here.
Air line (approximately)
74 kilometers
40 nautical miles