The calculated distance (air line) between Banja Luka and Mrkonjić Grad is approximately 26 miles respectively 41 kilometers.
By car or train, the actual journey to Mrkonjić Grad is certainly longer, as only the direct route (as the crow flies) between Banja Luka and Mrkonjić Grad has been calculated here.
Air line (approximately)
41 kilometers
22 nautical miles