The calculated distance (air line) between Nakhon Pathom and Kanchanaburi is approximately 36 miles respectively 57 kilometers.
By car or train, the actual journey to Kanchanaburi is certainly longer, as only the direct route (as the crow flies) between Nakhon Pathom and Kanchanaburi has been calculated here.
Air line (approximately)
57 kilometers
31 nautical miles