The calculated distance (air line) between Mariinskiy Posad and Ulyanovsk is approximately 126 miles respectively 203 kilometers.
By car or train, the actual journey to Ulyanovsk is certainly longer, as only the direct route (as the crow flies) between Mariinskiy Posad and Ulyanovsk has been calculated here.
Air line (approximately)
203 kilometers
110 nautical miles