Follow a worked example.
Every example below can be loaded using its calculator’s Reset example button. Inputs use centimetres, square centimetres or cubic centimetres as labelled, while angles use degrees.
From the side
Given: Side a = 5.
A = a²; P = 4a; d = a√2
| Measurement | Calculated value |
|---|---|
| Side | 5 cm |
| Area | 25 cm² |
| Perimeter | 20 cm |
| Diagonal | 7.0710678 cm |
From area
Given: Area A = 25.
a = √A
| Measurement | Calculated value |
|---|---|
| Side | 5 cm |
| Area | 25 cm² |
| Perimeter | 20 cm |
| Diagonal | 7.0710678 cm |
From the diagonal
Given: Diagonal d = 7.0710678119.
a = d/√2
| Measurement | Calculated value |
|---|---|
| Side | 5 cm |
| Area | 25 cm² |
| Perimeter | 20 cm |
| Diagonal | 7.0710678 cm |
From perimeter
Given: Perimeter P = 20.
a = P/4
| Measurement | Calculated value |
|---|---|
| Side | 5 cm |
| Area | 25 cm² |
| Perimeter | 20 cm |
| Diagonal | 7.0710678 cm |
Check the answer’s dimensions
An area contains a product of two lengths, while volume contains three. A perimeter or radius is still a length. If your input measurements are mixed between metres and centimetres, convert them to a common unit first. A realistic-looking number can still be wrong if the units were inconsistent.