Enter any one property of a square — side length, diagonal, perimeter, or area — and the Square Calculator computes all the remaining three values instantly. Choose your input type from the dropdown, enter your known measurement, and get back the side length (a), diagonal (q), perimeter (P), and area (A) in one click. Also try the Pythagorean Theorem Calculator.
Area (A)
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Side Length (a)
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Diagonal (q)
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Perimeter (P)
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The area of a square is calculated as A = a², where a is the side length. For example, if the side length is 5 meters, the area is 25 square meters. See also our Annulus Calculator.
The diagonal of a square is found using the formula q = a√2, where a is the side length. This comes from the Pythagorean theorem applied to the right triangle formed by two sides and the diagonal.
The perimeter of a square is P = 4a, where a is the side length. Since all four sides of a square are equal, you simply multiply the side length by 4.
If you know the area, the side length is a = √A (the square root of the area). For instance, if the area is 49 m², the side length is 7 m. You might also find our find Area with Ellipse Calculator useful.
Given the diagonal q, the side length is a = q / √2, which simplifies to a = q × (√2 / 2). For example, a diagonal of 7.071 m gives a side length of approximately 5 m.
Given the diagonal q, the perimeter is P = 4 × (q / √2) = 2q√2. Alternatively, given the perimeter P, the diagonal is q = (P/4) × √2.
Yes. From the perimeter P, the side length is a = P/4, the diagonal is q = (P/4)√2, and the area is A = (P/4)². Select 'Perimeter' from the dropdown and enter your value.
A square is a regular polygon with four equal sides and four right angles (90°). It is both a rectangle and a rhombus, and is one of the most fundamental shapes in geometry.