The calculated distance (air line) between Saint-Cyr-sur-Mer and Saint-Étienne is approximately 169 miles respectively 271 kilometers.
By car or train, the actual journey to Saint-Étienne is certainly longer, as only the direct route (as the crow flies) between Saint-Cyr-sur-Mer and Saint-Étienne has been calculated here.
Air line (approximately)
271 kilometers
146 nautical miles