The calculated distance (air line) between Hérouville-Saint-Clair and Saint-Quentin-en-Yvelines is approximately 110 miles respectively 177 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 Hérouville-Saint-Clair and Saint-Quentin-en-Yvelines has been calculated here.
Air line (approximately)
177 kilometers
95 nautical miles