The calculated distance (air line) between Nova Gradiška and Slavonski Brod is approximately 31 miles respectively 51 kilometers.
By car or train, the actual journey to Slavonski Brod is certainly longer, as only the direct route (as the crow flies) between Nova Gradiška and Slavonski Brod has been calculated here.
Air line (approximately)
51 kilometers
27 nautical miles