The calculated distance (air line) between Hainburg an der Donau and Meidling is approximately 28 miles respectively 45 kilometers.
By car or train, the actual journey to Meidling is certainly longer, as only the direct route (as the crow flies) between Hainburg an der Donau and Meidling has been calculated here.
Air line (approximately)
45 kilometers
25 nautical miles