Square: Area, Perimeter, Diagonal
Area is the side squared, perimeter is four times the side, and the diagonal is the side times √2 (about 1.414). That 41% extra length is what matters when you carry furniture through a doorway.
Your numbers
Area
144cm²
Perimeter
48cm
Diagonal
16.971cm
Formula
Area = Side ²
Area units are length squared: enter centimetres and you get cm², metres and you get m². Do not mix them.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Side (cm)One edge of a square or cube. | 12 | 0 and up |
Step by step
Quick reference table
Results when only Side (cm) changes and everything else stays put.
| Side (cm) | Area (cm²) | Perimeter (cm) | Diagonal (cm) |
|---|---|---|---|
| 6 | 36 | 24 | 8.485 |
| 9 | 81 | 36 | 12.728 |
| 12 | 144 | 48 | 16.971 |
| 18 | 324 | 72 | 25.456 |
| 24 | 576 | 96 | 33.941 |
What each result means
| Result | At default values |
|---|---|
| Area (cm²)The space a shape covers — length squared. | 144 |
| Perimeter (cm)The total length around the outside of a shape. | 48 |
| Diagonal (cm)Corner to opposite corner. | 16.971 |
Common mistakes
Area units are length squared: enter centimetres and you get cm², metres and you get m². Do not mix them.
Glossary
- Side
- One edge of a square or cube.
- Area
- The space a shape covers — length squared.
- Perimeter
- The total length around the outside of a shape.
- Diagonal
- Corner to opposite corner.
Frequently asked questions
Q. How is Square: Area, Perimeter, Diagonal calculated?
Area = Side ² — Area is the side squared, perimeter is four times the side, and the diagonal is the side times √2 (about 1.414). That 41% extra length is what matters when you carry furniture through a doorway.
Q. Can you walk through an example?
With Side 12cm, the answer is Area 144cm².
Q. What do I need to enter?
Enter Side. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Side (cm) moves the answer to Side (cm) 6 → Area (cm²) 36 and Side (cm) 24 → Area (cm²) 576. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Area units are length squared: enter centimetres and you get cm², metres and you get m². Do not mix them.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.