Rectangle Calculator
Calculate area, perimeter, and diagonal from length and width.
Formula
A = l×w, P = 2(l+w), d = √(l²+w²)
Area is length times width. Perimeter is twice the sum of length and width. Diagonal uses the Pythagorean theorem.
Examples
8×5 rectangle
10×4 rectangle
12×3 rectangle
Frequently Asked Questions
What is the area of a rectangle?
Area = length × width.
How do I find the diagonal of a rectangle?
Use the Pythagorean theorem: d = √(l² + w²).
What is the perimeter of a rectangle?
P = 2(l + w), the sum of all four sides.
About this Calculator
Calculate area, perimeter, and diagonal from length and width. All calculations are performed in your browser for instant results. Formulas are mathematically exact using JavaScript's built-in Math functions.