Square Calculator

A square is a four-sided polygon where all sides are equal in length and every interior angle is exactly 90 degrees. It is the simplest and most symmetric of all quadrilaterals, and three measurements follow directly from just one input, the side length: the area, the perimeter, and the diagonal. This calculator takes the side length and returns all three instantly, updating as you type. Area is the space inside the square, useful for calculating flooring, turf, paint coverage, or any surface application. Perimeter is the total length of the outer boundary, needed for fencing, framing, or bordering a square shape. The diagonal is the straight line from one corner to the opposite corner, cutting through the interior. Its length comes from applying Pythagoras to the two sides that form the right angle at any corner: the square root of side squared plus side squared, which simplifies to the side times the square root of two. This diagonal is always longer than the side by a factor of about 1.414, and it tells you the minimum width of a square opening needed to pass the square object through at an angle. Enter any positive side length and all three values appear immediately. All units are consistent: if the side is in metres, the area is in square metres and the diagonal and perimeter are in metres. The tool is useful for students learning plane geometry, for tradespeople calculating material quantities, for anyone sizing a square garden bed, tile layout, or panel, and for checking geometry homework quickly and accurately.