The calculated distance (air line) between Sint-Martens-Latem and Mouscron is approximately 26 miles respectively 43 kilometers.
By car or train, the actual journey to Mouscron is certainly longer, as only the direct route (as the crow flies) between Sint-Martens-Latem and Mouscron has been calculated here.
Air line (approximately)
43 kilometers
23 nautical miles