Projector and TV Screen Size Calculator

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Get the full dimensions of a screen from just one measurement. This screen size calculator is invaluable for anyone needing precise measurements for a monitor, TV or projector screen without the hassle of manual calculations.

Select the aspect ratio of your screen and enter one of the dimensions you know – diagonal, width or height.

STEP 1: ASPECT RATIO Select your screen aspect ratio (default 16:9)

STEP 2: SCREEN DIMENSIONS Select one of your screen dimensions
0″ 140″

0″ 140″

0″ 100″

Purpose of the Calculator

The screen dimensions calculator helps you understand the size of your screen – whether it’s a television, projector screen, or computer monitor.

Knowing the exact dimensions can be crucial for various reasons, like fitting it into a space, comparing models, or even for graphical design purposes.

If you want to know which size TV or screen is right for your room, check out the TV viewing distance calculator.

How It Works

The calculator operates on a simple principle: given one known screen dimension – its diagonal, width, or height – it can calculate the other two dimensions. This is particularly useful when you know just one measurement and need to find out the rest.

For more, check out how to measure a TV screen correctly.

Calculation Process

  1. Aspect Ratio Selection: The first step involves selecting the aspect ratio of your screen. Common aspect ratios like 4:3, 16:9, and 21:9 are available, covering most types of screens, from old TVs to modern ultrawide monitors. You can also choose between 2.35:1 and 2.39:1, which are popular movie aspect ratios.
  2. Inputting a Dimension: After selecting the aspect ratio, you input one of the three dimensions of your screen – either the diagonal, width, or height. This is done using the interactive sliders that allow you to specify the size.
  3. Automatic Calculation: Once a size is determined, the calculator automatically computes the other two dimensions based on the selected aspect ratio. This is done using geometric relationships inherent in the aspect ratio.

We use formulas derived from the Pythagorean theorem and the screen’s aspect ratio to calculate the screen dimensions based on a given diagonal, width, or height. The aspect ratio is the ratio of the width to the screen’s height.

First, these are the variables:

  • D: the diagonal of the screen
  • W: the width of the screen
  • H: the height of the screen
  • AR: the aspect ratio of the screen

For example, most modern widescreen TVs’ have a 16:9 aspect ratio.


    \[ AR = \frac{16}{9}  \]

Or, 1.78.

Formulas for Calculations

Here are the screen dimensions calculations if you want to work it out yourself.

1. Given the Diagonal (D)

When the diagonal is known, we can calculate the width and height using the aspect ratio and the Pythagorean theorem:

First, Width (W) from Diagonal:

    \[ W = \frac{D}{\sqrt{1 + \frac{1}{AR^2}}} \]

Then, Height (H) from Width: 

    \[ H = \frac{W}{AR} \]

Or, alternatively:

First, Height (H) from Diagonal:

    \[ H = \frac{D}{\sqrt{AR^2 + 1}} \]

Then, Width (W) from Height:

    \[ W = AR \times H \]

2. Given the Width (W)

If the width is known, we can calculate the diagonal and height:

First, Height (H) from Width:

    \[ H = \frac{W}{AR} \]

Then, Diagonal (D) from Width:

    \[ D = W \times \sqrt{1 + \frac{1}{AR^2}} \]

Or, alternatively:

First, Diagonal (D) from Width and Height:

    \[ D = \sqrt{W^2 + H^2} \]

Then, Height (H) from Width:

    \[ H = \frac{W}{AR} \]

3. Given the Height (H)

If the height is known, we calculate the width and diagonal as follows:

First, Width (W) from Height:

    \[ W = AR \times H \]

Then, Diagonal (D) from Height:

    \[ D = H \times \sqrt{AR^2 + 1} \]

Or, alternatively:

First, Diagonal (D) from Width and Height:

    \[ D = \sqrt{W^2 + H^2} \]

Then, Width (W) from Height:

    \[ W = AR \times H \]

Example Calculation

For example, if you have a 16:9 screen (where AR = 16/9)​ and you know the diagonal is 50 inches, you can calculate the width and height as follows:

First, Calculate Width (W) from Diagonal (D):

    \[ W = \frac{50}{\sqrt{1 + \left(\frac{9}{16}\right)^2}} \]

Then, Calculate Height (H) from Width (W):

    \[ H = \frac{W}{\frac{16}{9}} \]


Screen width = 43.6 inches | Screen height = 24.5 inches.

Or, you can use the calculator at the top of the page! 🙂

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About The Author

Paul started the Home Cinema Guide to help less-experienced users get the most out of today's audio-visual technology. He has been a sound, lighting and audio-visual engineer for around 20 years. At home, he has spent more time than is probably healthy installing, configuring, testing, de-rigging, fixing, tweaking, re-installing again (and sometimes using) various pieces of hi-fi and home cinema equipment. You can find out more here.

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