The calculated distance (air line) between Rouen and Saint-Quentin-en-Yvelines is approximately 62 miles respectively 100 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 Rouen and Saint-Quentin-en-Yvelines has been calculated here.
Air line (approximately)
100 kilometers
54 nautical miles