The calculated distance (air line) between Xam Nua and Luang Prabang is approximately 128 miles respectively 206 kilometers.
By car or train, the actual journey to Luang Prabang is certainly longer, as only the direct route (as the crow flies) between Xam Nua and Luang Prabang has been calculated here.
Air line (approximately)
206 kilometers
111 nautical miles