The calculated distance (air line) between Leixlip and An Muileann gCearr is approximately 36 miles respectively 59 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 Leixlip and An Muileann gCearr has been calculated here.
Air line (approximately)
59 kilometers
32 nautical miles