The calculated distance (air line) between Montesson and Rueil-Malmaison is approximately 3 miles respectively 5 kilometers.
By car or train, the actual journey to Rueil-Malmaison is certainly longer, as only the direct route (as the crow flies) between Montesson and Rueil-Malmaison has been calculated here.
Air line (approximately)
5 kilometers
3 nautical miles