The calculated distance (air line) between Montceau-les-Mines and Saint-Étienne is approximately 85 miles respectively 137 kilometers.
By car or train, the actual journey to Saint-Étienne is certainly longer, as only the direct route (as the crow flies) between Montceau-les-Mines and Saint-Étienne has been calculated here.
Air line (approximately)
137 kilometers
74 nautical miles