Rectangle Perimeter Calculator
Calculate rectangle perimeter from length and width, side and diagonal, side and area, or side and known perimeter.
Rectangle perimeter from length and width
The main English intent is to find perimeter from length and width. Extended modes cover common homework variants where one side is known with the diagonal, area, or perimeter.
| Known values | First step | Validation |
|---|---|---|
| Length and width | Use both sides directly | Both positive |
| Side and diagonal | Recover the missing side | Diagonal must be greater than the side |
| Side and area | Recover the missing side | Known side must be positive |
| Side and perimeter | Recover the missing side | Perimeter must be greater than twice the side |
Rectangle formulas
P is perimeter; l is length; w is width.
w is width; d is diagonal; l is known side.
w is width; A is area; l is known side.
Frequently Asked Questions
Sources and References
Calculations are based on the listed reference sources. Links open in a new tab.
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