The calculated distance (air line) between Champagne-au-Mont-d'Or and Saint-Étienne is approximately 32 miles respectively 51 kilometers.
By car or train, the actual journey to Saint-Étienne is certainly longer, as only the direct route (as the crow flies) between Champagne-au-Mont-d'Or and Saint-Étienne has been calculated here.
Air line (approximately)
51 kilometers
27 nautical miles