The calculated distance (air line) between Nakhon Luang and Krathum Baen is approximately 61 miles respectively 98 kilometers.
By car or train, the actual journey to Krathum Baen is certainly longer, as only the direct route (as the crow flies) between Nakhon Luang and Krathum Baen has been calculated here.
Air line (approximately)
98 kilometers
53 nautical miles