Perimeter Of Square Calculator

What this calculator does

So, you want the distance around a square. This tool finds it. Enter the length of one side, choose your unit, and it returns the perimeter, the total length of all four sides.

Because every side of a square is the same, you only need to measure one of them.

How to use it

1. Enter the side length of the square.
2. Choose the unit, then press Calculate.

What perimeter means

The perimeter of a shape is the distance all the way around its edge. For a square, it is how far you would travel by walking around all four sides and back to where you started. Since perimeter is a distance, it is measured in ordinary length units like centimetres or metres, not square units, which belong to area. It is worth keeping the two ideas apart: the perimeter is the length of the border, while the area is the space inside. This tool deals with the border.

Four equal sides

What makes a square so simple is that all four of its sides are exactly the same length. That is the defining feature of a square. So finding the perimeter needs no addition of different numbers: you just take one side and count it four times. The perimeter of a square is four times the length of a side, and the tool simply multiplies your single measurement by four. This is why a square is the easiest shape of all to find the perimeter of, and why you only have to measure one edge rather than several.

Finding the side from the perimeter

Because the relationship is so tidy, it works just as neatly in reverse. If you happen to know the perimeter of a square and want the length of one side, you divide the perimeter by four. So a square with a perimeter of 20 units has sides of 5 units each. This is handy in practice: if you know how much edging or fencing you have and want a square, dividing by four tells you how long each side can be. Multiplying by four and dividing by four are the two directions of the same simple rule.

A worked example

Take a square with a side of 5 units. Multiply the side by four to get 20, so the perimeter is 20 units. To check the reverse, divide that perimeter of 20 by four and you get back to a side of 5 units. The two operations undo each other exactly.

Squares and rectangles

A square is a special kind of rectangle, one whose length and width are equal. That connection shows up in the formulas. A rectangle's perimeter is two times the length plus two times the width; make the length and width the same, and that becomes four times the side, the square formula. So the square is the neat, symmetric case of the more general rectangle. If your shape has two different side lengths rather than four equal ones, the perimeter of a rectangle calculator is the tool to use instead.

Questions people ask

What is the perimeter of a square?

The total distance around its four sides, equal to four times the length of one side.

Why multiply the side by four?

Because all four sides of a square are equal, so the perimeter is one side counted four times.

How do I find the side from the perimeter?

Divide the perimeter by four. A perimeter of 20 units gives sides of 5 units.

Does the answer use square units?

No. Perimeter is a length, measured in plain units like metres or feet. Square units are for area.

What if the sides are not all equal?

Then it is a rectangle, and the perimeter of a rectangle calculator handles two different side lengths.

References

On the perimeter of a square. The perimeter is the distance around the boundary, equal to four times the side length.

1. Eric W. Weisstein, "Perimeter," from MathWorld, a Wolfram resource, on the perimeter as the length of a shape's boundary.
2. Eric W. Weisstein, "Square," from MathWorld, a Wolfram resource, on the square, a special case of the rectangle with four equal sides.