The calculated distance (air line) between Vang Vieng and Ban Houakhoua is approximately 159 miles respectively 255 kilometers.
By car or train, the actual journey to Ban Houakhoua is certainly longer, as only the direct route (as the crow flies) between Vang Vieng and Ban Houakhoua has been calculated here.
Air line (approximately)
255 kilometers
138 nautical miles