The calculated distance (air line) between Kowloon and Yuen Long San Hui is approximately 13 miles respectively 20 kilometers.
By car or train, the actual journey to Yuen Long San Hui is certainly longer, as only the direct route (as the crow flies) between Kowloon and Yuen Long San Hui has been calculated here.
Air line (approximately)
20 kilometers
11 nautical miles