The calculated distance (air line) between Kowloon and Yuen Long Kau Hui is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Yuen Long Kau Hui is certainly longer, as only the direct route (as the crow flies) between Kowloon and Yuen Long Kau Hui has been calculated here.
Air line (approximately)
21 kilometers
12 nautical miles