Square Area Calculator
Find the area, perimeter, and diagonal of a square from its side, area, or diagonal.
Last updated:
Input
Enter the side, area, or diagonal of a square to compute its area along with the perimeter and diagonal.
Value to enter
Result
Area S
100
Side a
10
Perimeter L
40
Diagonal d
14.142136
Length units match your input, and the area is in those units squared.
How it works
- The area of a square is S = a², where a is the side length.
- The perimeter is L = 4a and the diagonal is d = a times the square root of 2 (about 1.41421 times the side).
- To work back from the area use a = square root of S, and from the diagonal use a = d divided by the square root of 2.
- Length units match the input value, while the area is squared (for example a side in cm gives an area in cm²).
Frequently asked questions
- What formula gives the area of a square?
- With side a, the area is S = a². For example, a 5 cm side gives S = 5² = 25 cm². The perimeter L = 4a and the diagonal d = a√2 (about 1.41421 times the side) are shown too.
- How is this different from the rectangle area calculator?
- A square has all sides equal, so a single side a gives S = a². Use the rectangle calculator (height × width) when the two sides differ; a rectangle whose height and width are equal produces the same result as a square.
- Can I work backward from the area or diagonal to the side?
- Yes. From the area use a = √S, and from the diagonal use a = d ÷ √2. Enter any one of side, area, or diagonal and the tool computes the rest.
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