Square Perimeter Calculator

P = 4s. Four equal sides.

Inputs

Result

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How to use this calculator

  • Enter side length.
  • Read perimeter, area, diagonal.

About this calculator

A square is a regular quadrilateral — all four sides equal, all angles 90°. Perimeter = 4s; area = s²; diagonal = s√2. The square has the maximum area for any rectangle of fixed perimeter (proof: AM-GM inequality). Common everywhere: room layouts, tile patterns, chess boards.

Frequently asked

Is square a rectangle?+
Yes. Every square is a rectangle (opposite sides equal, angles 90°), but not every rectangle is a square.
What's the diagonal use?+
For laying out — checking corners are 90° (diagonal = s√2). Also for finding the longest item that fits.
Why is square optimal for area?+
For fixed perimeter, square maximizes area among rectangles. (Circle is overall optimal for any closed curve.)
Square vs cube?+
Square is 2D (perimeter, area). Cube is 3D (edge sum, surface area, volume). Different formulas.
Edge cases?+
s = 0 gives 0 perimeter. Negative s is geometrically invalid; calc clamps to ≥0.

Related calculators

Rectangle Perimeter Calculator
P = 2(l + w). Length plus width, doubled.
Area of a Rectangle Calculator
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Triangle Perimeter Calculator
P = a + b + c. Sum of all three sides.
Circle Circumference Calculator
C = 2πr (or πd). Area = πr². The fundamental circle formulas.
Trapezoid Perimeter Calculator
P = a + b + c + d. Sum of two parallel sides + two non-parallel.

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