The calculated distance (air line) between Vang Vieng and Muang Hôngsa is approximately 90 miles respectively 145 kilometers.
By car or train, the actual journey to Muang Hôngsa is certainly longer, as only the direct route (as the crow flies) between Vang Vieng and Muang Hôngsa has been calculated here.
Air line (approximately)
145 kilometers
78 nautical miles