The calculated distance (air line) between Phetchaburi and Krathum Baen is approximately 43 miles respectively 69 kilometers.
By car or train, the actual journey to Krathum Baen is certainly longer, as only the direct route (as the crow flies) between Phetchaburi and Krathum Baen has been calculated here.
Air line (approximately)
69 kilometers
37 nautical miles