The calculated distance (air line) between Čapljina and Mrkonjić Grad is approximately 94 miles respectively 152 kilometers.
By car or train, the actual journey to Mrkonjić Grad is certainly longer, as only the direct route (as the crow flies) between Čapljina and Mrkonjić Grad has been calculated here.
Air line (approximately)
152 kilometers
82 nautical miles