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Projector Calculator

Created by Bogna Szyk
Last updated: Jun 05, 2023

If you ever wanted to set up a home cinema, we've got you covered. This projector calculator is a handy tool that determines the perfect viewing distance (that is, the distance between the screen and your amazingly comfortable couch), the ideal throw distance (the distance between the screen and the projector), and the optimal brightness. With our help, setting up your personal movie theater becomes a piece of cake!

While this calculator is dedicated to projectors, if you want to choose the perfect TV screen size, be sure to head to our TV size calculator.

Setting up your screen

Your first step towards setting up the perfect home cinema should be to properly calculate the viewing distance. If you're sitting too far from the screen, you will not see every minute detail. On the other hand, if you're sitting too close to the screen, the whole picture might not fit in your field of view; for example, if you're concentrating on the left part of the screen, you won't notice what's happening on the right.

🙋 To set the proper vertical position, you may find our TV mounting height calculator helpful.

To find out the proper viewing distance, fill in the screen properties: the resolution of your movie, the aspect ratio of the screen, and its diagonal size. These three basic values are vital for determining the optimal setup of your home cinema.

Our projector screen calculator will automatically determine the following values:

  • Minimum viewing distance - The minimum distance between you and the screen to ensure the whole picture is in your field of view. Don't place any seats closer to the screen than this, as viewers will find it uncomfortable to watch the movie.
  • Maximum viewing distance - The maximum allowable distance between the audience and the screen, according to THX (an American audio-video company). For the movie theater to obtain the THX certification, the audience must sit at this distance or closer to the screen.
  • Optimal viewing distance (quality-wise) - Regardless of the field of view, this value specifies the distance between the audience and the screen that ensures they see all available detail. The higher the resolution, the closer to the screen you should sit. Hence, if sitting at the optimal distance would mean you sit too close to the screen to get the whole picture in your field of view, you can decrease the image quality without affecting viewing quality.

🙋 To evaluate the aspect ratio by yourself, try Omni's aspect ratio calculator.

You can also open the advanced mode to get more information on recommended viewing distances:

  • Maximum viewing distance recommended by THX - Apart from setting a maximum allowable viewing distance, THX also specifies the maximum recommended distance. They suggest that sitting at this distance to the screen (or closer) will result in optimal viewing conditions.
  • Maximum viewing distance recommended by SMPTE - Similarly, SMPTE (Society of Motion Picture and Television Engineers) recommends a maximum viewing distance that should ensure optimal viewing quality in a home theater.

Determining the screen brightness

The next step in setting up the perfect home cinema is to choose the proper projector to ensure correct brightness levels. First, you need to input the following values:

  • Projector brightness - You can find it in the manufacturer's specifications of your projector. It is expressed in ANSI lumens and describes how bright the image projected by the device is.
  • Screen gain - If you use a special material for your screen, it can increase or decrease the brightness of the projected image. For example, the Stewart FireHawk screen provides a maximum gain in the brightness of 1.1, while the Da-lite High Power Screen can offer as much as 2.8.

Our projector calculator estimates the screen's brightness in fL (foot-Lamberts). You can also switch the units to cd/m² (candelas per square meter) should you choose to use SI units. The brightness levels are as follows:

  • Brightness lower than 12 fL is not acceptable, even in totally dark rooms - your audience will have problems with watching a movie that dark. You should consider a brighter projector or a smaller screen.
  • Brightness between 12 and 16 fL is better but still too low for dark rooms.
  • Brightness between 16 and 22 fL is perfect for completely dark rooms. If this is the brightness level you got from our projector screen calculator, you can be proud of yourself!
  • Brightness higher than 22 fL is recommended for rooms with some ambient light. If you plan to have a lot of light in the room, you should consider increasing the brightness even more.

🙋 Feel free to check our lighting calculator to get more insights about lighting principles for other applications.

Setting up the projector

The third and final part of our projector throw calculator deals with the throw distance, or, in other words, the distance between the projector and the screen. To calculate it, you will need to read the manufacturer's specifications for your projector and find a value called the throw ratio.

Essentially, the throw ratio is the proportion between the throw distance D and the width of the screen W. You can write it down as throw ratio = D/W.

The manufacturer of each projector specifies two values: the minimum and maximum throw ratio. After you input these values into the projector calculator, you will obtain the minimum and maximum throw distance perfect for your screen dimensions. Now all you have to do is set up the home cinema according to the results you got.

Still not satisfied?

There's a lot more to setting up your perfect home movie theater - perhaps you want to calculate the number of seating rows or try to ensure that audience members' vision in the last row is not blocked. Make sure to take a look at the Carlton Bale's website, who provides a lot of helpful tips and an elaborate calculating tool on which this projector calculator is based.

Bogna Szyk
Screen properties
Aspect ratio
16:9 HDTV
Screen diagonal
Viewing distances
Ideal (quality-wise)
Viewing brightness
Projector brightness
ANSI lumens
Screen gain
The screen is...
Projector - manufacturer's specifications
Min. throw ratio
Max. throw ratio
Throw distance for your screen
Min. throw distance
Max. throw distance
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