How do I find the area of a square?
Multiply the side by itself. A square with 5 cm sides has an area of 5 x 5 = 25 cm squared. Every side is equal, so you only need one measurement.
// maths › 2D Shapes
Square Area Calculator
Find the area, perimeter and diagonal of a square from its side length.
area = side² ; perimeter = 4×side ; diagonal = side×√2
Frequently asked questions
What is the diagonal of a square?
The line from one corner to the opposite corner. It equals the side times the square root of 2 (about 1.414), because the diagonal splits the square into two right triangles.
Why is the diagonal longer than the side?
Because it cuts straight across the square rather than along an edge. Pythagoras tells us it is the square root of two sides squared, which always beats a single side.
What units does the area come out in?
Square units of whatever you put in. Sides in metres give area in square metres; sides in inches give square inches. The calculator just follows your input.
Where is this useful?
Tiling a square floor, sizing a square plot of land, or working out fabric for a square cloth. The diagonal helps when you need to fit a square through a doorway.