The calculated distance (air line) between Montmorillon and Saint-Quentin-en-Yvelines is approximately 171 miles respectively 275 kilometers.
By car or train, the actual journey to Saint-Quentin-en-Yvelines is certainly longer, as only the direct route (as the crow flies) between Montmorillon and Saint-Quentin-en-Yvelines has been calculated here.
Air line (approximately)
275 kilometers
148 nautical miles