The calculated distance (air line) between Kozarska Dubica and Banja Luka is approximately 33 miles respectively 54 kilometers.
By car or train, the actual journey to Banja Luka is certainly longer, as only the direct route (as the crow flies) between Kozarska Dubica and Banja Luka has been calculated here.
Air line (approximately)
54 kilometers
29 nautical miles