Calculating Projector Screen Dimensions for 16:9 Projectors

Here are your basic formulas for calculating projector screen dimensions. They are slightly rounded for your convenience.

All calculations are based on the screen area, and do not include the borders or frame.
These calculations are for standard 16:9 aspect ratio screens (HDTV shape), which are used by the vast majority of home theater users, as the vast marjority of home theater projectors are 16:9 native aspect ratio.

Simply put, a 16:9 projection screen is 1.78 times as wide as it is high. 16 / 9 = 1.78 (rounded)

If you know your projector screen’s diagonal size:

Projector Screen Height: To calculate the projector screen height, multiply the diagonal by approximately 0.495. (In other words the height of the screen is just a bit less than 50% of the diagonal.

Projector Screen Width: The width of the projector screen is approximately 87% of the projector screen’s diagonal, so multiply the diagonal measurement by approximately 0.87.

Diagonal Size of a home theater projector screen: 100″

Projector screen height: 0.495 x 100″ = 49.5 inches
Projector screen width: 0.87 x 100″ = 87 inches

Diagonal Size of a home theater projection screen: 110″

Projector screen height: 0.495 x 110″ = 54.5″
Projector screen width: 0.87 x 110″ = 95.7″

If you know projection screen width, and need to calculate diagonal size and height of the screen:

Projector screen diagonal: To calculate the projector screen diagonal from the known width, divide the width by 0.87
Projector screen height: To calculate the projection screen height, from the known width, multiply the width by 0.57


Width of a home theater projector screen: 100″

Projector screen diagonal: 100″ / 0.87 = 115″
Projector screen height: 100″ * 0.57 = 57″

Width of a home theater projection screen: 80″

Projector screen diagonal: 80 ” / 0.87 = 92 ”
Projector screen height: 80 ” * 0.57 = 45.6 ”

It’s that easy.

News And Comments

  • Peter Swiggs

    you have your maths wrong as a 16:9 image has a height higher than half the width 0.495 is less than half. 16/2=8 not higher than 9


      Peter, I’m looking at your two posts. I’m not sure what you are saying is wrong. You say:

      16:9 image has a height higher than half the width 0.495 is less than half.

      But what I said is 0.495 is height compared to diagonal, NOT compared to width.

      As you can see for height compared to width, I’m using 0.57, which (as you point out) is larger than 50%

      As to your image of a monitor, It looks like you are using numbers that include the case, not just the display. That would distort your square root numbers, but there’s also a separate issue. Many monitors/HDTVs have display areas that are not 16:9, in ratio, only close. They simply use only the 16:9 (or in the case of commercial monitors – 16:10. We own a Sony LCDTV that has a surface area of the display that’s larger than the used area. Only slightly of course, but that isn’t uncommon.

      So, even if those measurements on your monitor image are correct in that they represent only the screen, not the bezel, that still typically does not mean that the actual LCD display is a true 16:9 (or 16:10), only that it only uses the 16:9 or 16:10 and the rest stays blank.

      For example, this right off one of the screen manufacturer’s pages:
      100” diagonal Viewing Surface Dimensions 87.2 inches wide by 49.0 inches high
      seems everyone rounds… Using their numbers and the Theorem, squaring both and adding them, you get 10,004, which is a tiny fraction over 100” (100×100 = 10,000).

      Now, if I am overlooking something in my article, a typo or such, please do point it out. But on rescanning it, it looks right to me. -art

  • Peter Swiggs

    This shows that the maths is wrong via pythagoras’s thereom:
    37.2 squared = 1383.84
    22.1 squared = 488.41
    together they = 1872.25
    the square root of that = 43.27 to 2dp the diagonal of tv n casing
    43.27 * 0.495 = 21.42 to 2dp not 22.1
    2dp equals 2 decimal places.
    images is at: