The calculated distance (air line) between Zaječar and Sremska Mitrovica is approximately 150 miles respectively 242 kilometers.
By car or train, the actual journey to Sremska Mitrovica is certainly longer, as only the direct route (as the crow flies) between Zaječar and Sremska Mitrovica has been calculated here.
Air line (approximately)
242 kilometers
131 nautical miles