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Rectangle Area Calculator

Calculate the area, perimeter, and diagonal of a rectangle from its width and height.

 

 

Area
Perimeter
Diagonal

About this calculator

Use this calculator to find the area, perimeter, and diagonal of a rectangle from width and height. It applies to rooms, screens, sheets of paper, plots, and any other right-angled four-sided shape. If width and height are equal, the shape is a square.

The formulas are: area = width × height, perimeter = 2 (width + height), and diagonal = √(width² + height²). Use the same length unit for both sides. Area is then in that unit squared, while perimeter and diagonal stay in the original length unit.

Width: One side of the rectangle.

Height: The adjacent side, in the same unit as the width.

Area: The interior of the rectangle.

Perimeter: The total length around the four sides.

Diagonal: The straight-line distance between opposite corners.