The calculated distance (air line) between Piranshahr and Ṟuwandiz is approximately 35 miles respectively 56 kilometers.
By car or train, the actual journey to Ṟuwandiz is certainly longer, as only the direct route (as the crow flies) between Piranshahr and Ṟuwandiz has been calculated here.
Air line (approximately)
56 kilometers
30 nautical miles