The calculated distance (air line) between Nakhon Si Thammarat and Phuket is approximately 114 miles respectively 183 kilometers.
By car or train, the actual journey to Phuket is certainly longer, as only the direct route (as the crow flies) between Nakhon Si Thammarat and Phuket has been calculated here.
Air line (approximately)
183 kilometers
99 nautical miles