Square perimeter calculator

Q: What is the square perimeter formula?

The direct formula is P = 4·a. With the diagonal you get the side by dividing it by the square root of 2, and with the area you find the side by taking the square root before multiplying by four.

Compute square perimeter from side or diagonal. Includes unit conversions and decimal control.

Square perimeter calculator

Compute the perimeter from the side, the diagonal or a known area.

Get the main perimeter plus equivalent side, diagonal and area, with instant conversions to mm, cm, m, in and ft.

Inputs

Method

Side Diagonal Area

Side e.g. 5.3

Comma or dot decimals are accepted.

Units

The main perimeter will be displayed in the chosen unit.

Decimals 0–10

Rounding applied to every result.

Results

Main perimeter

Enter your data and press Calculate

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Side (a)

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Diagonal (d)

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Area (A)

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Formula

P = 4a

Perimeter conversions

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How to calculate the perimeter of a square

The perimeter of a square is four times its side: P = 4·a. If you know the diagonal, recover the side by dividing that measurement by the square root of 2. When you start from an area, take the square root of the area to find the side before applying the perimeter formula.

This calculator normalizes the unit you enter (mm, cm, m, in or ft), finds the equivalent side, diagonal and area, and shows the main perimeter in your chosen unit. Everything is rounded to the decimals you set so you can copy the results straight away.

Worked example

Take a square with a 5.3 cm side. The perimeter is \( P = 4 · 5.3 = 21.2\ \text{cm} \). The diagonal is \( 5.3·\sqrt{2} ≈ 7.495\ \text{cm} \) and the area \( 5.3^2 ≈ 28.09\ \text{cm}^2 \). With this tool you can see all those equivalents also in meters, inches or feet.

Which values can I enter?

You can start from the side, the diagonal or a known area. Pick a method, set the unit and the calculator will return the perimeter plus the equivalent measurements.

What is the square perimeter formula?

The direct formula is P = 4·a. With the diagonal you get the side by dividing it by the square root of 2, and with the area you find the side by taking the square root before multiplying by four.

Which units are supported?

It works with meters, centimeters, millimeters, inches and feet. Results and conversions are shown in mm, cm, m, in and ft with a selectable precision between 0 and 10 decimals.