<Tr> <Td> 1 acre in...</Td> <Td>... is equal to...</Td> </Tr> <Tr> <Th> SI units </Th> <Td> 4,046.9 m </Td> </Tr> <P> The acre is a unit of land area used in the imperial and US customary systems . It is defined as the area of 1 chain by 1 furlong (66 by 660 feet), which is exactly equal to ​ ⁄ of a square mile, 43,560 square feet, approximately 4,047 m, or about 40% of a hectare . </P> <P> The acre is commonly used in Antigua and Barbuda, American Samoa, the Bahamas, Belize, the British Virgin Islands, the Cayman Islands, Canada, Dominica, the Falkland Islands, Grenada, Ghana, Guam, the Northern Mariana Islands, India, Sri Lanka, Bangladesh, Nepal, Ireland, Jamaica, Montserrat, Myanmar, Pakistan, Samoa, St. Lucia, St. Helena, St. Kitts and Nevis, St. Vincent and the Grenadines, Turks and Caicos, the United Kingdom, the United States and the US Virgin Islands . </P>

How big is 1 acre in square feet