The calculated distance (air line) between Ban Houayxay and Luang Namtha is approximately 79 miles respectively 127 kilometers.
By car or train, the actual journey to Luang Namtha is certainly longer, as only the direct route (as the crow flies) between Ban Houayxay and Luang Namtha has been calculated here.
Air line (approximately)
127 kilometers
69 nautical miles