The calculated distance (air line) between Yuen Long San Hui and Choi Wun is approximately 13 miles respectively 22 kilometers.
By car or train, the actual journey to Choi Wun is certainly longer, as only the direct route (as the crow flies) between Yuen Long San Hui and Choi Wun has been calculated here.
Air line (approximately)
22 kilometers
12 nautical miles