The calculated distance (air line) between Lenart v Slov. Goricah and Postojna is approximately 95 miles respectively 153 kilometers.
By car or train, the actual journey to Postojna is certainly longer, as only the direct route (as the crow flies) between Lenart v Slov. Goricah and Postojna has been calculated here.
Air line (approximately)
153 kilometers
83 nautical miles