answer by sdlombardi confidence votes 105 because an acre is a measure of area not length it is defined in square feet an acre can be of any shape so long as its area is exactly 43560 square feet the most standard shape for an acre is one furlong by one chain or 660 feet by 66 feet square with this size is about 60 24 yards on a side or a little less than 181 feet 1 yard by 3630 y ards 30 yards by 121 yards there are lots of shapes that are 3 4 of an acre