The calculated distance (air line) between Sint-Martens-Lennik and Charleroi is approximately 30 miles respectively 49 kilometers.
By car or train, the actual journey to Charleroi is certainly longer, as only the direct route (as the crow flies) between Sint-Martens-Lennik and Charleroi has been calculated here.
Air line (approximately)
49 kilometers
26 nautical miles