Irish measure or plantation measure was a system of units of land measurement used in Ireland from the 16th century plantations until the 19th century, with residual use into the 20th century. The units were based on "English measure" but used a linear perch measuring 7 yards (6.4 m) as opposed to the English rod of 5.5 yards (5.0 m). Thus, linear units such as the furlong and mile, which were defined in terms of perches, were longer by a factor of 14:11 in Irish measure, while units of area, such as the rood or acre, were larger by 196:121. The Weights and Measures Act 1824 mandated the use throughout the British Empire of "Imperial measure", also called "statute measure", based on English measure. Imperial measure soon replaced Irish measure in the use of the Dublin Castle administration, but Irish measure persisted in local government, and longer still in private use.

Plantations in 16th- and 17th-century Ireland involved the confiscation of Irish-owned land by the English Crown and the colonisation of this land with settlers from Great Britain. The Crown saw the plantations as a means of controlling, anglicising and 'civilising' Gaelic Ireland. The main plantations took place from the 1550s to the 1620s, the biggest of which was the plantation of Ulster. The plantations led to the founding of many towns, massive demographic, cultural and economic changes, changes in land ownership and the landscape, and also to centuries of ethnic and sectarian conflict. They took place before and during the earliest English colonisation of the Americas, and a group known as the West Country Men were involved in both Irish and American colonization.