The calculated distance (air line) between Tuen Mun and Pok Fu Lam is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Pok Fu Lam is certainly longer, as only the direct route (as the crow flies) between Tuen Mun and Pok Fu Lam has been calculated here.
Air line (approximately)
21 kilometers
11 nautical miles