The calculated distance (air line) between Tullamore and Dún Laoghaire is approximately 56 miles respectively 90 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Tullamore and Dún Laoghaire has been calculated here.
Air line (approximately)
90 kilometers
49 nautical miles