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