how far should projector be from 100 inch screen

 

If you are trying to find the perfect size for your projector, there are a few things that should be taken into account including how far the viewer will be from the screen and how large you would like your projected image to appear.

A good starting point is to calculate the ratio of screen size (in inches) and distance from projector (in feet). For instance if you have an 80" screen and your viewers will be 4-5 feet away then the ratio is 4:1. If you have a 100" screen and viewers will be 10 feet then it's 10:1. It doesn't matter if this sounds confusing because this link can help with conversion for any size projection screens:

Now that you have the ratio, you can use it as a guide to help decide how large a screen size is appropriate with your specific application.

 

Image source: https://www.amazon.in/

For instance if you have an 80" screen and viewers will be 4-5 feet away then the ratio is 4:1. As described above, this means that if your viewing distance is 6 feet, then the ideal screen size for this application would be 120-inches (4 x ratio of screen size to viewing distance). This will ensure that all viewers can see at least 75% of the image at all times. If the ratio is 6:1 then the ideal screen size would be 60-inches (6 x ratio of screen size to viewing distance). Again, you can see that this can make a huge difference in the image.

If you have a 100" screen and viewers will be 10 feet away then the ratio is 10:1. As described above, this means that if your viewing distance is 8 feet, then the ideal screen size for this application would be 160-inches (10 x ratio of screen size to viewing distance). If your viewing distance was 12 feet, then you would want at least an image of 200-inches (10 x ratio of screen size to viewing distance). Obviously, these are just general guidelines and some factors may influence the choice. For instance if you are projecting an image of a room in your home, then this application would dictate a larger screen size.

 

Image source: https://www.flipkart.com/

Once you have the ratio and have calculated your optimal configuration based on the viewing distance and screen size, you can make a few calculations so that you can figure out the approximate cost of your setup. For instance if you have a 4:1 ratio and need as large an image as possible but still only want to use 12 foot viewing distance (based on the example above), then it's simple math: 120-inches ÷ 4 = 40 inches which is about 40% of the total image height. As you can see, this is just a rough estimate but it should be relatively easy to find a consumer projector that offers this ratio.

You may be thinking that this ratio sounds like a lot of math and you may be right, but it is the best way to determine the size that is most suitable for your application. You may also find it helpful to think about these ratios in physical terms to make it easier. For instance if you are using a large home theater screen such as 120-inches or bigger, then 40% of the screen length is equivalent to 5-6 feet. It's short enough so that all viewers can see both eyes clearly on a 120" screen.