The calculated distance (air line) between Nizhniy Novgorod and Zelenodolsk is approximately 177 miles respectively 285 kilometers.
By car or train, the actual journey to Zelenodolsk is certainly longer, as only the direct route (as the crow flies) between Nizhniy Novgorod and Zelenodolsk has been calculated here.
Air line (approximately)
285 kilometers
154 nautical miles