The calculated distance (air line) between Horn and Klagenfurt am Wörthersee is approximately 154 miles respectively 248 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 Horn and Klagenfurt am Wörthersee has been calculated here.
Air line (approximately)
248 kilometers
134 nautical miles