Square Perimeter Calculator — P = 4 × Side
Enter the side length of a square and instantly get the perimeter (P = 4s), area (s²), and diagonal (s√2). Works in any unit — centimetres, metres, inches, feet — just keep all measurements consistent.
Total distance around the square (P = 4 × side)
- 1
Side length
5 - 2
Perimeter
4 × 5 = 20A square has 4 equal sides, so the perimeter is four times the side length.
How does this calculator work?
The perimeter of a square is 4 times the side length (P = 4s). Enter the side to get the perimeter, area (s²), and diagonal (s√2) instantly. To work backwards from the perimeter, divide by 4 to find the side. Works for any unit — cm, m, in, ft.
Formula
How this is calculated
A square has four equal sides and four right angles. Its perimeter — the total distance around the outside — is simply four times one side: P = 4s. Because all sides are identical, you only need to measure one side and multiply by 4.
The area equals the side squared (s²), and the diagonal (connecting two opposite corners) equals s × √2, derived from the Pythagorean theorem applied to the 45–45–90 right triangle that a diagonal creates.
To reverse the calculation — finding the side length from the perimeter — divide by 4: s = P ÷ 4. The calculator assumes a perfect flat square with all sides exactly equal. Real-world measurements (fencing, flooring, framing) should include a small margin for cuts and joins.
Frequently asked questions
P = 4 × side. Since all four sides of a square are equal, you multiply the length of one side by 4. For example, a square with a 7 cm side has a perimeter of 28 cm.
Rearrange the formula: side = P ÷ 4. If the perimeter is 24 m, each side is 6 m. This also means the area is 36 m² and the diagonal is 6√2 ≈ 8.485 m.
Perimeter (4s) measures the total boundary length in linear units (m, ft, etc.). Area (s²) measures the surface it covers in square units (m², ft², etc.). A 5 m square has a perimeter of 20 m and an area of 25 m².
Also known as
TG we-Calculate Editorial Team. (2026). Square Perimeter Calculator — P = 4 × Side [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/square-perimeter-calculator
TG we-Calculate Editorial Team. "Square Perimeter Calculator — P = 4 × Side." TG we-Calculate. 2026. https://we-calculate.com/calculator/square-perimeter-calculator.
TG we-Calculate Editorial Team, "Square Perimeter Calculator — P = 4 × Side," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/square-perimeter-calculator
@misc{wecalculate_square_perimeter_calculator, title = {Square Perimeter Calculator — P = 4 × Side}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/square-perimeter-calculator}}, year = {2026}, note = {TG we-Calculate} }
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