Mathematics, Statistics & Geometry

Area of Rectangle Calculator

Calculate the area, perimeter, and diagonal of any rectangle instantly. The simplest and fastest geometry tool on the web.

Area
50
Perimeter30
Diagonal11.18
Calculation StepsWidth (w) = 10 Height (h) = 5 Area = w * h = 10 * 5 = 50.000000 Perimeter = 2(w + h) = 2(10 + 5) = 30.000000 Diagonal = √(w² + h²) = √(10² + 5²) = 11.180340

Calculated locally in your browser. Fast, secure, and private.

The Essential Rectangle Tool

The Area of Rectangle calculator is the fundamental tool for measuring four-sided shapes with 90-degree corners. Whether you are flooring a room, sizing a website banner, or calculating land area, this calculator provides instant results for area, perimeter, and diagonal length.

A=w×h\begin{aligned} A = w \times h \end{aligned}

Where:
A=
The total surface space inside the rectangle
w=
The horizontal dimension of the rectangle
h=
The vertical dimension of the rectangle

Step-by-Step Calculation

  1. Measure the Width: The horizontal distance.
  2. Measure the Height: The vertical distance.
  3. Multiply: Width × Height = Area.
  4. Perimeter: 2 × (Width + Height).

Why the Diagonal Matters

The diagonal of a rectangle is the straight-line distance between opposite corners. In construction, measuring both diagonals and ensuring they are equal is the standard way to verify that a structure is "square" (has perfect 90-degree corners).

Practical Applications

  • Real Estate: Calculating the square footage of rooms and properties.
  • Printing: Determining the surface area of paper for ink estimation.
  • Screen Design: Sizing UI elements and calculating aspect ratios.
  • Shipping: Finding the surface area of boxes for labeling.

Frequently Asked Questions

Multiply the width by the height. The formula is A = w × h.

The perimeter is the distance around the edge, calculated as 2 × (width + height).

Use the Pythagorean theorem: d = √(w² + h²).

Yes. A square is a special type of rectangle where the width and height are equal.

Area is measured in square units, such as square meters (m²) or square inches (in²).

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