The calculated distance (air line) between Pathum Thani and Samut Prakan is approximately 29 miles respectively 47 kilometers.
By car or train, the actual journey to Samut Prakan is certainly longer, as only the direct route (as the crow flies) between Pathum Thani and Samut Prakan has been calculated here.
Air line (approximately)
47 kilometers
25 nautical miles