The calculated distance (air line) between Pattaya and Phra Nakhon Si Ayutthaya is approximately 100 miles respectively 161 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 Pattaya and Phra Nakhon Si Ayutthaya has been calculated here.
Air line (approximately)
161 kilometers
87 nautical miles