The calculated distance (air line) between Marchtrenk and Klagenfurt am Wörthersee is approximately 109 miles respectively 175 kilometers.
By car or train, the actual journey to Klagenfurt am Wörthersee is certainly longer, as only the direct route (as the crow flies) between Marchtrenk and Klagenfurt am Wörthersee has been calculated here.
Air line (approximately)
175 kilometers
94 nautical miles