The calculated distance (air line) between Nam Định and Hai Bà Trưng is approximately 45 miles respectively 73 kilometers.
By car or train, the actual journey to Hai Bà Trưng is certainly longer, as only the direct route (as the crow flies) between Nam Định and Hai Bà Trưng has been calculated here.
Air line (approximately)
73 kilometers
39 nautical miles