The calculated distance (air line) between Dien Bien Phu and Muang Xay is approximately 82 miles respectively 133 kilometers.
By car or train, the actual journey to Muang Xay is certainly longer, as only the direct route (as the crow flies) between Dien Bien Phu and Muang Xay has been calculated here.
Air line (approximately)
133 kilometers
72 nautical miles