The calculated distance (air line) between Miklavž na Dravskem Polju and Postojna is approximately 87 miles respectively 140 kilometers.
By car or train, the actual journey to Postojna is certainly longer, as only the direct route (as the crow flies) between Miklavž na Dravskem Polju and Postojna has been calculated here.
Air line (approximately)
140 kilometers
76 nautical miles