📏 Enter known values
Formula Reference
Worked example
If we use the result to calculate Side, we should get the value you entered:
How to calculate the perimeter of a square
A square has four equal sides, so its perimeter is four times the side:
\[ P = 4 \times \text{Side} \]
And the side is the perimeter divided by four:
\[ \text{Side} = \frac{P}{4} \]
How to use the calculator
- Enter the side to get the perimeter, or the perimeter to get the side.
- Leave the other field empty.
- Press Calculate. The perimeter is in the same unit as the side.
Worked examples
1. Square with a side of 7 cm
\[ P = 4 \times 7 = 28\ \text{cm} \]
2. Side of a square with a perimeter of 50 m
\[ \text{Side} = \frac{50}{4} = 12.5\ \text{m} \]
3. Perimeter from the area
A square room has an area of 16 m². Its side is \( \sqrt{16} = 4 \) m, so its perimeter is \( 4 \times 4 = 16 \) m.
4. Perimeter from the diagonal
The diagonal of a square is \( \text{Side} \times \sqrt{2} \). If a square tile has a diagonal of 42.4 cm, its side is \( 42.4 \div 1.414 \approx 30 \) cm and its perimeter is about 120 cm.
Perimeter, area and diagonal of a square
| Side | Perimeter | Area | Diagonal |
|---|---|---|---|
| 1 | 4 | 1 | 1.41 |
| 2 | 8 | 4 | 2.83 |
| 3 | 12 | 9 | 4.24 |
| 4 | 16 | 16 | 5.66 |
| 5 | 20 | 25 | 7.07 |
| 6 | 24 | 36 | 8.49 |
| 7 | 28 | 49 | 9.9 |
| 8 | 32 | 64 | 11.31 |
| 9 | 36 | 81 | 12.73 |
| 10 | 40 | 100 | 14.14 |
When the side doubles, the perimeter doubles too, but the area is multiplied by four.
When Do You Need to Calculate the Perimeter of a Square?
Raised beds and planters are often square. The perimeter tells you how many boards or edging pieces you need to frame them.
Quick material count for a garden projectSquare photos, canvases and mirrors need a frame along all four sides. The perimeter gives the molding length before adding the corners.
Cut frames to sizeSquare quilt blocks, coasters and napkins get binding or trim around the edge. The perimeter sets how much ribbon or bias tape to buy.
Buy the right amount of trimSquare plots, boxing rings and some play areas are fenced or roped along their perimeter.
Plan rope, fencing or marking tapeIn cities with square blocks, one lap around the block is its perimeter. Knowing it helps you plan a walk or a run of a given distance.
Plan training distancesThe perimeter of a square is one of the first formulas students learn. Exercises often combine it with the area to find the side.
Practice with multiplication and square rootsCommon Mistakes
⚠️ Confusing Perimeter and Area
⚠️ Square Units
⚠️ Using the Diagonal as the Side
⚠️ Dividing by 2 Instead of 4
⚠️ Not Checking It Is a Square
⚠️ Mixed Units
Applications by Industry
Construction
- Columns: Formwork around square columns
- Tiling: Edge trim for square tiled areas
- Fencing: Fences around square lots
Gardening
- Raised beds: Boards to frame square beds
- Lawns: Edging around square lawns
- Greenhouses: Base frame of square greenhouses
Crafts & Textiles
- Quilts: Binding around square blocks
- Napkins: Hem length for square napkins and scarves
- Frames: Molding for square canvases
Manufacturing
- Tubing: Perimeter of square tubes to work out the surface to paint
- Seals: Gaskets for square lids and hatches
- Packaging: Tape needed to seal square boxes
Electronics
- Chips: Perimeter of square chips to fit the pins along the edge
- Boards: Edge length of square circuit boards
- Enclosures: Sealing strips for square cases
Education
- Primary school: First perimeter formulas
- Algebra: Solving for the side from the perimeter
- Comparisons: How the area grows faster than the perimeter
External Resources
- Square properties, perimeter and area — Math is Fun
- Square definition and properties — Wikipedia