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