The calculated distance (air line) between Rennes and Saint-Quentin-en-Yvelines is approximately 175 miles respectively 282 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 Rennes and Saint-Quentin-en-Yvelines has been calculated here.
Air line (approximately)
282 kilometers
152 nautical miles