The calculated distance (air line) between Mechelen-aan-de-Maas and Liège is approximately 24 miles respectively 38 kilometers.
By car or train, the actual journey to Liège is certainly longer, as only the direct route (as the crow flies) between Mechelen-aan-de-Maas and Liège has been calculated here.
Air line (approximately)
38 kilometers
20 nautical miles