The calculated distance (air line) between Kosum Phisai and Khon Kaen is approximately 21 miles respectively 33 kilometers.
By car or train, the actual journey to Khon Kaen is certainly longer, as only the direct route (as the crow flies) between Kosum Phisai and Khon Kaen has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles