The calculated distance (air line) between Roubaix and Marquette-lez-Lille is approximately 5 miles respectively 8 kilometers.
By car or train, the actual journey to Marquette-lez-Lille is certainly longer, as only the direct route (as the crow flies) between Roubaix and Marquette-lez-Lille has been calculated here.
Air line (approximately)
8 kilometers
4 nautical miles