The calculated distance (air line) between Podčetrtek and Slovenj Gradec is approximately 35 miles respectively 56 kilometers.
By car or train, the actual journey to Slovenj Gradec is certainly longer, as only the direct route (as the crow flies) between Podčetrtek and Slovenj Gradec has been calculated here.
Air line (approximately)
56 kilometers
30 nautical miles