The calculated distance (air line) between Sha Tau Kok and Mong Kok is approximately 16 miles respectively 26 kilometers.
By car or train, the actual journey to Mong Kok is certainly longer, as only the direct route (as the crow flies) between Sha Tau Kok and Mong Kok has been calculated here.
Air line (approximately)
26 kilometers
14 nautical miles