What is the formula for the area of a square?

Area = s², where s is the side length. For example, a square with a side of 5 meters has an area of 25 square meters.

How do I find the side length from the area?

Take the square root of the area: s = √Area. For example, if the area is 49 sq ft, the side length is √49 = 7 ft.

What is the diagonal of a square?

The diagonal connects two opposite corners and equals s × √2 ≈ s × 1.41421. For a square with side 10, the diagonal is approximately 14.14.

What is the perimeter of a square?

Perimeter = 4 × s. A square with side 6 cm has a perimeter of 24 cm.

What units does this calculator use?

The calculator is unit-agnostic. If you enter the side in meters, the area is in square meters, the perimeter in meters, and the diagonal in meters. Use any consistent unit.

How is a square different from a rectangle?

A square is a special rectangle where all four sides are equal. Its area formula (s²) is a simplified version of the rectangle formula (length × width).

Area of a Square Calculator

Enter a side length to get the area, perimeter, and diagonal of a square — or enter the area to find the side.

Calculate From

Side Length (s)

units

Formulas

Area A = s²

Perimeter P = 4s

Diagonal d = s√2

Side from Area s = √A

Enter a value on the left to calculate

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Summary

This calculator solves all the key measurements of a square in one step. Enter the side length and instantly get the area (s²), perimeter (4s), and diagonal (s√2). You can also work in reverse — enter the area and the tool calculates the corresponding side length and the other properties. All calculations run in your browser with no data sent to a server.

How it works

Choose whether to start from the side length or the area.
Enter your known value in the input field.
The calculator instantly computes all remaining properties.
Read off area, perimeter, and diagonal with the formula breakdown shown.
Click "Copy Results" to copy all values to your clipboard.

Use cases

Calculate floor or land area for square-shaped spaces.
Find the perimeter of a square room or garden plot.
Determine how long the diagonal of a square tile or panel is.
Work backwards from a known area to find the required side length.
Verify geometry homework answers instantly.
Use in construction, carpentry, or landscaping measurements.
Convert square footage or square meters to a side length.
Explore how area and perimeter scale with side length.

Frequently Asked Questions

Last updated: 2026-05-28 · Reviewed by Nham Vu