The calculated distance (air line) between Šentilj v Slov. Goricah and Celje is approximately 36 miles respectively 58 kilometers.
By car or train, the actual journey to Celje is certainly longer, as only the direct route (as the crow flies) between Šentilj v Slov. Goricah and Celje has been calculated here.
Air line (approximately)
58 kilometers
31 nautical miles