The calculated distance (air line) between Caudebec-lès-Elbeuf and Nantes is approximately 185 miles respectively 298 kilometers.
By car or train, the actual journey to Nantes is certainly longer, as only the direct route (as the crow flies) between Caudebec-lès-Elbeuf and Nantes has been calculated here.
Air line (approximately)
298 kilometers
161 nautical miles