The calculated distance (air line) between L'Haÿ-les-Roses and Cergy-Pontoise is approximately 21 miles respectively 35 kilometers.
By car or train, the actual journey to Cergy-Pontoise is certainly longer, as only the direct route (as the crow flies) between L'Haÿ-les-Roses and Cergy-Pontoise has been calculated here.
Air line (approximately)
35 kilometers
19 nautical miles