Zoning Unit is a term used to describe a unit of measurement for land area. An ACRE is a unit of measurement for land area that is equal to 43, 560 square feet or 4, 047 square meters. It is commonly used in the United States and other countries to measure the size of a parcel of land. Zoning Units are often used in zoning regulations to determine the size of a building or structure that can be built on a particular piece of land.