The calculated distance (air line) between Pak Kret and Krathum Baen is approximately 24 miles respectively 39 kilometers.
By car or train, the actual journey to Krathum Baen is certainly longer, as only the direct route (as the crow flies) between Pak Kret and Krathum Baen has been calculated here.
Air line (approximately)
39 kilometers
21 nautical miles