The calculated distance (air line) between Saint-Quentin-en-Yvelines and Créteil is approximately 20 miles respectively 33 kilometers.
By car or train, the actual journey to Créteil is certainly longer, as only the direct route (as the crow flies) between Saint-Quentin-en-Yvelines and Créteil has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles