The calculated distance (air line) between Nakhon Nayok and Krathum Baen is approximately 74 miles respectively 120 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 Nayok and Krathum Baen has been calculated here.
Air line (approximately)
120 kilometers
65 nautical miles