The calculated distance (air line) between Rostov-na-Donu and Zernograd is approximately 38 miles respectively 62 kilometers.
By car or train, the actual journey to Zernograd is certainly longer, as only the direct route (as the crow flies) between Rostov-na-Donu and Zernograd has been calculated here.
Air line (approximately)
62 kilometers
33 nautical miles