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