The calculated distance (air line) between Bandon and Dún Laoghaire is approximately 153 miles respectively 246 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Bandon and Dún Laoghaire has been calculated here.
Air line (approximately)
246 kilometers
133 nautical miles