If the shape of the acre of land is a perfect square, then the dimension is 208.71 feet by 208.71 feet. An acre is an area of land that measures 43,560 square feet. Half an acre would be half that or divide by 2. It depends if it is a rectangle or square to begin with, but the square feet or yards or meters would be the same amount.
Around 22000 square feet. Most house lots are approximately a quarter acre, (newer more high density areas, around one 10th acre) for comparison purposes.