The calculated distance (air line) between Saint-Étienne and Aix-en-Provence is approximately 142 miles respectively 228 kilometers.
By car or train, the actual journey to Aix-en-Provence is certainly longer, as only the direct route (as the crow flies) between Saint-Étienne and Aix-en-Provence has been calculated here.
Air line (approximately)
228 kilometers
123 nautical miles