The calculated distance (air line) between Khlong Luang and Phra Nakhon Si Ayutthaya is approximately 20 miles respectively 33 kilometers.
By car or train, the actual journey to Phra Nakhon Si Ayutthaya is certainly longer, as only the direct route (as the crow flies) between Khlong Luang and Phra Nakhon Si Ayutthaya has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles