Calculators
Rectangle Calculator
Calculate rectangle area, perimeter, and diagonal from length and width locally in your browser.
Enter a length and a width from 0 (exclusive) to 1000000000 to see the area (length x width), perimeter (2 x (length + width)), diagonal, and shape. The calculation runs locally in your browser; your values are not uploaded or stored.
Find rectangle measurements without uploading anything.
Enter a length and a width from 0 (exclusive) to 1000000000 to see the area, perimeter, diagonal, and shape. Everything runs locally in your browser, so your values are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What does the rectangle calculator show?
Enter a length and a width from 0 (exclusive) to 1000000000. The calculator returns the area (length times width), the perimeter (2 times length plus width), the diagonal (square root of length squared plus width squared), and the shape (square when both sides are equal, otherwise rectangle). For example, length 5 and width 3 give area 15, perimeter 16, diagonal about 5.83095189485, and rectangle shape.
Which formulas does the rectangle calculator use?
It uses area = length x width, perimeter = 2 x (length + width), and diagonal = square root of (length squared + width squared) from the Pythagorean theorem. The shape is square when length equals width and rectangle otherwise.
Which inputs are accepted?
Enter a length and a width greater than zero through 1000000000. Decimal values are accepted. Zero, negative numbers, non-numeric text, and values above the limit show a clear error instead of a result.
Do my numbers stay private?
Yes. The calculation and copy action run locally in your browser. CodeASystem does not upload or store the values you enter.