The calculated distance (air line) between Samut Prakan and Lop Buri is approximately 83 miles respectively 134 kilometers.
By car or train, the actual journey to Lop Buri is certainly longer, as only the direct route (as the crow flies) between Samut Prakan and Lop Buri has been calculated here.
Air line (approximately)
134 kilometers
72 nautical miles