How To Calculate Projector Screen Size?

For most items, you’ll typically see the dimensions listed as a dimension, that is, one number for the length and another for width. For projectors, however, you’ll only see one measurement under “screen size. The first step is determining what size it is referring to and how you can extrapolate the remainder of the image’s size from this data.

Like televisions, projector images are measured in diagonal. The diagonal measurement can also be used to determine the dimensions of screens. If you’re trying to know the dimensions to align your projector with the appropriate screen or even to compare one display with another, you’ll usually do it using this data.

Extrapolating Length and Width

Content of different types comes with different aspect ratios. HD films and TV shows are 16:9 in aspect. If you’re trying to replicate the experience of a real theater, then you’ll require an aspect ratio for cinemas of 2.35:1.

If you’re familiar with that Pythagorean theorem, you could utilize that and the aspect ratio to determine the precise dimensions of the screen or image. You can also locate the tool to calculate the aspect ratio online if you’re not a mathematician.

What about the throw ratio?

Another aspect that complicates the issue regarding screen dimensions is that, unlike televisions, the screen size of a projector isn’t static. The size of the image created by a lamp in a projector will vary based on how far the lamps are from the screens.

The benefit is knowing that this ratio doesn’t alter; it’s simply the magnitude. In that sense, the size and length will grow and decrease at the same rate. It is possible to determine how much the screen size changes when moving it by using the throwing ratio.

Throw ratios of the projector can be expressed as a decimal calculated by dividing the size of your image. As you can see, when looking at a diagram, an additional zoom-in could confuse. However, generally speaking, the greater the separation between the projector and its lens, the bigger the screen you’ll require.

So how do you calculate a projector screen’s size?

As you will observe, several factors are at play, and you might require some math to figure out the answer. Three equations will have to understand:

  • The ratio of throwing is expressed by T=W/D. The throwing ratio (T) will be equal to the length (W) multiplied by the distance (D).
  • The aspect ratio is: For HD content, this ratio is 16:9. On the cinema screen, it is 2.35:1.
  • The Pythagorean Theorem: Typically written as A2+B2=C2, it might be more helpful to think of it as W2+H2=S2, or width2+height2=screen size2.

If you’re aware of the location, you’ll place your projector, take note of the distance between it and your wall, and then multiply that measurement with the ratio of the throw. Utilize the aspect ratio of your screen to determine the height. Then apply it to solve the Pythagorean Theorem to determine the size of the screen.

There is also the other direction. If you have a spot that you want to decorate, you can measure the space and determine the size you’d like your picture to be. You can use painter’s paper to draw out the location you see in your picture (using an aspect ratio to calculate your dimensions).

 Determine the size of your screen through an equation called the Pythagorean Theorem. You could multiply the size by a throw to determine how far from the projector should be.

It could seem complicated initially, but once you’ve done it, it’s pretty easy to calculate the size of your projector’s screen. Making the calculations to determine your screen size before purchasing and installing your equipment could help you avoid a lot of time and effort in the longer term.

Thank you so much for reading this article, I hope you like and it may help you in solving your problems. Take care

Jonathan Holmes
Jonathan Holmes is a projector enthusiast and expert based in the United Kingdom. As the founder and editor of, Jonathan provides detailed buying guides, reviews, and advice to help consumers find the perfect projector for their needs. With over a decade of experience testing and researching projectors, Jonathan takes pride in being an industry insider. He stays up-to-date on all the latest projector models and technologies to provide readers with accurate, hands-on information.