The calculated distance (air line) between Donnybrook and An Muileann gCearr is approximately 48 miles respectively 78 kilometers.
By car or train, the actual journey to An Muileann gCearr is certainly longer, as only the direct route (as the crow flies) between Donnybrook and An Muileann gCearr has been calculated here.
Air line (approximately)
78 kilometers
42 nautical miles