The calculated distance (air line) between Al Ḩudaydah and Sa'dah is approximately 158 miles respectively 253 kilometers.
By car or train, the actual journey to Sa'dah is certainly longer, as only the direct route (as the crow flies) between Al Ḩudaydah and Sa'dah has been calculated here.
Air line (approximately)
253 kilometers
137 nautical miles