The calculated distance (air line) between Neustadt an der Donau and Wiesbaden is approximately 181 miles respectively 291 kilometers.
By car or train, the actual journey to Wiesbaden is certainly longer, as only the direct route (as the crow flies) between Neustadt an der Donau and Wiesbaden has been calculated here.
Air line (approximately)
291 kilometers
157 nautical miles