European size unit, abbreviated as ESU, is a standard gross margin of EUR 1 200 that is used to express the economic size of an agricultural holding or farm.
For each activity (or 'enterprise') on a farm (for example wheat production, dairy cows or the output from a vineyard), the standard gross margin (SGM) is estimated based on the area used for the particular activity (or the number of heads of livestock) and a regional coefficient. The sum of all such margins derived from activities on a particular farm is its economic size, which is then expressed in European size units (by dividing the total SGM in euro by 1200, thus converting it to ESU).