The calculated distance (air line) between Douvres-la-Délivrande and Nantes is approximately 153 miles respectively 247 kilometers.
By car or train, the actual journey to Nantes is certainly longer, as only the direct route (as the crow flies) between Douvres-la-Délivrande and Nantes has been calculated here.
Air line (approximately)
247 kilometers
133 nautical miles