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