Cultivated organic soils, which are a large source of CO2 emissions, are of particular interest in the Republic of Ireland where peatlands cover 20 % of the landscape. For accurate accounting and national reporting of greenhouse gas (GHG) emissions, there is a need to calculate the total land area used for cultivation activity on drained organic soils. Peatlands (organic soils) in Ireland are also used for arable farming, which results in particularly high greenhouse gas emissions per unit area. However, the Irish National Inventory Report to the United Nations Framework Convention on Climate Change lacks mention of this type of land use. The actual area of organic soils under arable land use (cropland) in Ireland has, thus far, not been quantified. Here we provide a first estimate of the area of organic soil that is used for arable farming in Ireland. Through map overlay analysis using GIS in combination with probability sampling and ground truthing, we estimate the area of organic soils under arable cropping at 1,235 ha, which is considerably lower than the estimate of 3,688 ha based on map overlays alone. This research provides information to support improved accounting of organic soils under cultivation and may contribute to reducing uncertainty in national reporting of GHG emissions, thus providing a more reliable basis for strategies aimed at reducing GHG emissions in Ireland in the future.