The calculated distance (air line) between Saint-Jean-de-la-Ruelle and Nantes is approximately 166 miles respectively 268 kilometers.
By car or train, the actual journey to Nantes is certainly longer, as only the direct route (as the crow flies) between Saint-Jean-de-la-Ruelle and Nantes has been calculated here.
Air line (approximately)
268 kilometers
145 nautical miles