The calculated distance (air line) between Rostov-na-Donu and Novocherkassk is approximately 22 miles respectively 35 kilometers.
By car or train, the actual journey to Novocherkassk is certainly longer, as only the direct route (as the crow flies) between Rostov-na-Donu and Novocherkassk has been calculated here.
Air line (approximately)
35 kilometers
19 nautical miles