The calculated distance (air line) between Prakhon Chai and Khlong Luang is approximately 170 miles respectively 273 kilometers.
By car or train, the actual journey to Khlong Luang is certainly longer, as only the direct route (as the crow flies) between Prakhon Chai and Khlong Luang has been calculated here.
Air line (approximately)
273 kilometers
148 nautical miles