The calculated distance (air line) between Saint-Quentin-en-Yvelines and Neuilly-sur-Seine is approximately 14 miles respectively 22 kilometers.
By car or train, the actual journey to Neuilly-sur-Seine is certainly longer, as only the direct route (as the crow flies) between Saint-Quentin-en-Yvelines and Neuilly-sur-Seine has been calculated here.
Air line (approximately)
22 kilometers
12 nautical miles