Perimeter of Square Calculator
Enter the side length of a square to find its perimeter.
Updated
Perimeter of Square Calculator
Our Perimeter of Square Calculator finds the perimeter of a square from its side length, in any unit. It also shows the working, the area, the diagonal and the perimeter in other units, with a labelled drawing. Use it for geometry homework, fencing, tiles, frames and room borders.
Quick answer
The perimeter of a square is 4 times the side length: P = 4 × 6 = 24 cm.
- Formula: P = 4s = s + s + s + s
- Side from perimeter: s = P ÷ 4
- From the area: P = 4 × √A
- Units: the perimeter is a length, so cm stays cm (not cm²)
What Is the Perimeter of a Square?
A square is a four-sided shape with four equal sides and four right angles. Its opposite sides are parallel, and its two diagonals are equal and cross at right angles. The perimeter is the total distance around the outside, so it is the four sides added together.
Perimeter of a Square Formula
P = s + s + s + s
Because all four sides are the same length, adding them up is the same as multiplying one side by 4.
- Measure one side. s = 6 cm.
- Multiply by 4. 4 × 6 = 24.
- Write the answer in the same unit. 24 cm.
Square Perimeter Examples
| Side | Perimeter |
|---|---|
| 6 cm | 4 × 6 = 24 cm |
| 10 m | 4 × 10 = 40 m |
| 8.5 in | 4 × 8.5 = 34 in |
| 3.25 ft | 4 × 3.25 = 13 ft |
| 1/2 mi | 4 × 0.5 = 2 mi |
Decimals and fractions work the same way: the perimeter is always 4 times the side, in the side's unit.
Finding the Side from the Perimeter
36 ÷ 4 = 9
Divide the perimeter by 4 to undo the formula. A square with a perimeter of 36 m has sides of 9 m. If you know the area instead, take the square root to get the side, then multiply by 4: an area of 49 m² gives s = 7 m and P = 28 m.
Perimeter vs Area
The perimeter is the distance around a shape (a length, such as m). The area is the space inside it (square units, such as m²). When the side of a square doubles, the perimeter doubles too, but the area becomes four times as large. A square with side 4 has P = 16 and A = 16, the only square where the two numbers match.
Common Mistakes
- Squaring the side: s² is the area, not the perimeter. A 6 cm square has P = 24 cm, not 36.
- Counting only some sides: a square has four sides, so multiply by 4, not 2.
- Square units: a perimeter is a length (cm, m, ft), not an area (cm²).
- Using the diagonal: the diagonal is longer than a side (s × √2). Convert it first: s = d ÷ √2.
- Counting a shared wall: for fencing along a house, leave out the side that is not fenced.
Key Terms
- Side
- Any one of the four equal edges, s.
- Perimeter
- The distance all the way around, P = 4s.
- Area
- The space inside, A = s², in square units.
- Diagonal
- The line between opposite corners, d = s × √2.
How to Use the Perimeter of Square Calculator
- Enter the side length. Type the length of one side, such as 6. Decimals and fractions such as 3/4 work.
- Pick a unit. Choose a unit if you want one (mm, cm, m, km, in, ft, yd or mi). The perimeter is given in the same unit.
- Read and copy the result. The perimeter appears as you type, with a labelled drawing, the working, the area, the diagonal and the perimeter in other units. Press Copy to copy it, or Clear or Esc to start again.
Example: a square garden has sides of 7.5 m. Enter 7.5 and pick m. The perimeter is 4 × 7.5 = 30 m, so you need 30 m of fencing to go all the way around.
Who Can Use This Calculator?
Frequently Asked Questions (FAQs)
How do you find the perimeter of a square?
Multiply the side length by 4. A square with 6 cm sides has a perimeter of 4 × 6 = 24 cm.
What is the formula for the perimeter of a square?
P = 4s, where s is the length of one side. It is the same as adding the four equal sides: s + s + s + s.
How do you find the side of a square from its perimeter?
Divide the perimeter by 4: s = P ÷ 4. A perimeter of 36 m gives a side of 9 m.
How do you find the perimeter of a square from its area?
Take the square root of the area to get the side, then multiply by 4: P = 4 × √A. An area of 49 m² gives s = 7 m and P = 28 m.
What is the difference between perimeter and area of a square?
The perimeter is the distance around the square, 4s, in units such as m. The area is the space inside, s², in square units such as m². A 10 m square has P = 40 m and A = 100 m².
How do you find the perimeter of a square from its diagonal?
Divide the diagonal by √2 to get the side, then multiply by 4: P = 4d ÷ √2 = 2√2 × d. A diagonal of 10 cm gives P ≈ 28.28 cm.
Is the Perimeter of Square Calculator free?
Yes. It is completely free, needs no sign-up, and can be used as many times as you like.
Try our Perimeter of Square Calculator to find the perimeter of any square from its side length, in any unit.