The calculated distance (air line) between Saint-Omer and Cergy-Pontoise is approximately 118 miles respectively 191 kilometers.
By car or train, the actual journey to Cergy-Pontoise is certainly longer, as only the direct route (as the crow flies) between Saint-Omer and Cergy-Pontoise has been calculated here.
Air line (approximately)
191 kilometers
103 nautical miles