Speed limits in Ireland

Sign at the Irish border indicating that limits in the Republic of Ireland are denominated in km/h; Road speed limits in the United Kingdom (of which Northern Ireland is part) are given in miles per hour. Without this reminder, a motorist might mistakenly think that the sign indicates a limit of 100 mph (160 km/h).

Speed limits in Ireland apply on all public roads in the state. These are signposted and legislated for in kilometres per hour. Speed limits are demarcated by regulatory road signs. These consist of white circular signs with a red outline. Speed limits are marked in black with "km/h" below the speed limit. Smaller "repeater" speed limit signs are used along stretches of road where there is no change in speed limit, in order to remind motorists currently on the road and to inform traffic merging from junctions that a certain speed limit applies.