The calculated distance (air line) between Pong Nam Ron and Krathum Baen is approximately 144 miles respectively 232 kilometers.
By car or train, the actual journey to Krathum Baen is certainly longer, as only the direct route (as the crow flies) between Pong Nam Ron and Krathum Baen has been calculated here.
Air line (approximately)
232 kilometers
125 nautical miles