The calculated distance (air line) between Ballinasloe and Dún Laoghaire is approximately 86 miles respectively 138 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Ballinasloe and Dún Laoghaire has been calculated here.
Air line (approximately)
138 kilometers
75 nautical miles