The calculated distance (air line) between Sankt Veit an der Glan and Mödling is approximately 128 miles respectively 206 kilometers.
By car or train, the actual journey to Mödling is certainly longer, as only the direct route (as the crow flies) between Sankt Veit an der Glan and Mödling has been calculated here.
Air line (approximately)
206 kilometers
111 nautical miles