An acre is a unit of land area used in the British imperial and the United States customary systems. It is traditionally defined as the area of one chain by one furlong (66 by 660 feet), which is exactly equal to 10 square chains, 1/640 of a square mile, 4,840 square yards, or 43,560 square feet. An acre can be of any shape, from rectangles to circles, or even hexagons, and it can have any length and width so long as the total area of land is 43,560 square feet. The most standard shape for an acre is one furlong by one chain, or 660 feet by 66 feet. To find the linear measurements of other rectangular acres, just divide 43,560 by the number of feet you want on one side. A square-shaped acre would then be about 208.7 by 208.7 feet (because 208.7 x 208.7 = ~43,560). An acre 100 feet wide would be 435.6 feet long (100 x 435.6 = 43,560) and an acre 1 foot wide would be 43,560 feet long.