Square area, perimeter and diagonal calculator
Choose the one value you know about the square, enter it, and the tool works out the rest.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter known value, value and length unit.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Area = side², perimeter = 4 × side and diagonal = side × √2. From the diagonal, side = d ÷ √2; from the area, side = √A.
Example
Inputs: Known value = Side, Value = 4, Length unit = Centimeters (cm). Result: Area: 16 cm²; Side: 4 cm; Perimeter: 16 cm.
Limits and caveats
- When you enter an area it is in the square of the chosen unit.
- The unit choice only labels the results.
Questions about this tool
What is the formula for the area of a square?
Area equals the side times itself. A square with 4 cm sides has an area of 16 cm².
How do I get the area from the diagonal?
Area equals the diagonal squared divided by 2. A diagonal of 10 gives an area of 50.
How do I get the side from the area?
Take the square root of the area. An area of 49 means a side of 7.