The calculated distance (air line) between Soisy-sous-Montmorency and Saint-Ouen is approximately 6 miles respectively 9 kilometers.
By car or train, the actual journey to Saint-Ouen is certainly longer, as only the direct route (as the crow flies) between Soisy-sous-Montmorency and Saint-Ouen has been calculated here.
Air line (approximately)
9 kilometers
5 nautical miles