# Width of a Rectangle Calculator

Table of contents

How to use the width of a rectangle calculator?How do I calculate the width of a rectangle?Related calculatorsFAQsThe **width of a rectangle calculator** can take two dimensions of your rectangle (height, area, diagonal, or perimeter) and **work out the width of your rectangle**. We'll also show you some **formulas for the width of a rectangle**, that are based on what information you have available. So don't be a square and read on!

## How to use the width of a rectangle calculator?

Using the **width of a rectangle calculator** is easy, with only two steps. Here's how.

**Enter the dimensions**that you know of the rectangle.**Find your rectangle width**in the bottom box.- The calculator is
**omni-directional**— if you want to work backwards instead, you can change the rectangle's width and see how its other dimensions react. - And that's it! Now you know
**how to calculate the width of a rectangle!**

## How do I calculate the width of a rectangle?

**Depending on what information you have available**, there are many ways to calculate the width of a rectangle.

- If you have the area
`A`

and length`h`

, its width`w`

is`w = A/h`

. - If you have the perimeter
`P`

and length`h`

, its width is`w = P/2−h`

. - If you have the diagonal
`d`

and length`h`

, it's width can be found with`w = √(d²−h²)`

. - If the rectangle's length is not known, you'd need to do some algebra with the quadratic equation to solve for the width.

That's a lot of **different formulas** for the width of a rectangle! It's because there are multiple equations that govern **the dimensions of a rectangle**. Here they are:

where:

- $w$ is the rectangle's
**width**; - $h$ is the rectangle's
**length**; - $A$ is the rectangle's
**area**; - $P$ is the rectangle's
**perimeter**; and - $d$ is the length of the rectangle's
**diagonal**(as described by the Pythagorean theorem).

Here's a neat visual:

### What is the width of a rectangle?

A rectangle has four sides, but because the sides are paired, there are **only two unique dimensions**. Conventionally, **the width is the shortest** of these two dimensions, but when the rectangle is presented as lying on its side, **the horizontal side** is usually called the width.

### What is the width of a rectangle with length 4 m and area 20 m?

Using **the formula for a rectangle's area**, `A = h × w`

, we can follow these steps:

- Rewrite the area formula to make the width
`w`

the subject of the equation:`w = A/h`

. - Plug in the values:
`w = 20/4`

. - Do the math and find that
`w = 5 m`

.