The calculated distance (air line) between Al Ḩudaydah and Dhamār is approximately 99 miles respectively 159 kilometers.
By car or train, the actual journey to Dhamār is certainly longer, as only the direct route (as the crow flies) between Al Ḩudaydah and Dhamār has been calculated here.
Air line (approximately)
159 kilometers
86 nautical miles