projection screen format ratio 

If you have read our How to Select a Projector Screen Guide, you most likely have a good idea how to go about selecting a projection screen. One of the essential steps is determining which size screen you need. We carry an assortment of screens from future screen and other brand , and each screen is offered in a variety of sizes. Sizes are broken down into formats: video or NTSC (4:3), HDTV (16:9), widescreen (1.85:1), square or slides (1:1), and various AV formats. The guide below will help you understand what format and size will best fit your situation.
Projector Screen Formats and Education
creen formats are determined by the specific aspect ratio of the screen. Aspect ratio is the fractional relation of the width of a video image compared to its height. The two most common aspect ratios in home video are 4:3 (also known as 4x3, 1.33:1, or standard) and 16:9 (16x9, 1.78:1, or wide-screen). All the older TVs and computer monitors you grew up with had the squarish 4:3 shape--only 33 percent wider than it was high. On the other hand, 16:9 is the native aspect ratio of most HDTV programming; it is 78 percent wider than it is tall, or fully one-third wider than 4:3.
So which aspect ratio is best for you? Today, the most commonly sold aspect ratios screens for home theaters are 1.78:1 (16:9) and now growing 2.35:1 (Cinema Scope). 16:9 aspect ratio screens are a perfect match to today's HD video projectors.
To figure out what aspect ratio may be best for you, you may consider the following:
If you are building a dedicated room geared mostly towards movie watching, then we would suggest a 2.40/2.35 Aspect Ratio screen since this is what most movies are usually shot in. However, when you watch 16:9 and 4:3 aspect ratio content on your 2.35/2.40 projection screen, you will have black bars on the left and right of the projected image.

If you are purchasing a screen for a media room or primary viewing of HDTV channels and video game playing, then we would suggest a 1.78:1 (16:9) projection screen. However, when you watch 2.35 and 1.85 movies you will have black bars above and below your projected image. When watching 4:3 content, you will have black bars on the sides of your projected image.