The calculated distance (air line) between Monfalcone and Reggio nell'Emilia is approximately 161 miles respectively 258 kilometers.
By car or train, the actual journey to Reggio nell'Emilia is certainly longer, as only the direct route (as the crow flies) between Monfalcone and Reggio nell'Emilia has been calculated here.
Air line (approximately)
258 kilometers
139 nautical miles