The calculated distance (air line) between Le Blanc-Mesnil and Fontenay-sous-Bois is approximately 6 miles respectively 10 kilometers.
By car or train, the actual journey to Fontenay-sous-Bois is certainly longer, as only the direct route (as the crow flies) between Le Blanc-Mesnil and Fontenay-sous-Bois has been calculated here.
Air line (approximately)
10 kilometers
5 nautical miles