The calculated distance (air line) between Saint-Florent-sur-Cher and Nantes is approximately 180 miles respectively 289 kilometers.
By car or train, the actual journey to Nantes is certainly longer, as only the direct route (as the crow flies) between Saint-Florent-sur-Cher and Nantes has been calculated here.
Air line (approximately)
289 kilometers
156 nautical miles