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