The calculated distance (air line) between Bukit Mertajam and Kuala Selangor is approximately 149 miles respectively 240 kilometers.
By car or train, the actual journey to Kuala Selangor is certainly longer, as only the direct route (as the crow flies) between Bukit Mertajam and Kuala Selangor has been calculated here.
Air line (approximately)
240 kilometers
130 nautical miles