The calculated distance (air line) between Kai Tak and Tin Shui Wai is approximately 15 miles respectively 25 kilometers.
By car or train, the actual journey to Tin Shui Wai is certainly longer, as only the direct route (as the crow flies) between Kai Tak and Tin Shui Wai has been calculated here.
Air line (approximately)
25 kilometers
13 nautical miles