The calculated distance (air line) between Serendah and Bukit Mertajam is approximately 159 miles respectively 256 kilometers.
By car or train, the actual journey to Bukit Mertajam is certainly longer, as only the direct route (as the crow flies) between Serendah and Bukit Mertajam has been calculated here.
Air line (approximately)
256 kilometers
138 nautical miles