The calculated distance (air line) between Knjazevac and Smederevska Palanka is approximately 85 miles respectively 137 kilometers.
By car or train, the actual journey to Smederevska Palanka is certainly longer, as only the direct route (as the crow flies) between Knjazevac and Smederevska Palanka has been calculated here.
Air line (approximately)
137 kilometers
74 nautical miles