The calculated distance (air line) between Banatski Karlovac and Zrenjanin is approximately 39 miles respectively 62 kilometers.
By car or train, the actual journey to Zrenjanin is certainly longer, as only the direct route (as the crow flies) between Banatski Karlovac and Zrenjanin has been calculated here.
Air line (approximately)
62 kilometers
34 nautical miles