Acre is a unit of land area in the inch-pound system of measurement. One acre equals 160 square rods or 43,560 square feet (4046.856 square meters). An acre that is square in shape measures about 208.7 feet (63.6 meters) on each side. There are 640 acres in a square mile. In the metric system, one measure of land area is the hectare, which equals 10,000 square meters, or 2.471 acres.
