The calculated distance (air line) between Thái Nguyên and Lạng Sơn is approximately 61 miles respectively 99 kilometers.
By car or train, the actual journey to Lạng Sơn is certainly longer, as only the direct route (as the crow flies) between Thái Nguyên and Lạng Sơn has been calculated here.
Air line (approximately)
99 kilometers
53 nautical miles