One of the most frequent questions we get is, “How big should my screen be?” Although this is not an overly complicated question to answer, determining the right projection screen size does require a few additional queries to reach the proper conclusion.

Here are the major considerations to determine your optimum projection screen size.

What kind of content will be projected, and what level of audience engagement is required? The ANSI/AVIXA DISCAS (Display Image Size for 2D Content in Audiovisual Systems) standard identifies two main viewing categories: Basic Decision Making, or BDM, and Analytical Decision Making (ADM).

  • BDM: The viewer can make basic decisions based on the displayed image. The decisions are not dependent on critical details within the image, but the viewer can assimilate and retain information. The viewer is actively engaged with the content (information displays, presentations containing detailed images, product illustrations, etc. in classrooms, boardrooms, or multi-purpose rooms,).
  • ADM: The viewer is fully engaged with minute details and needs to be able to resolve every element of the displayed image. Analytical decision-making environments support critical assessments, including medical imaging, fine arts, engineering or architectural drawings, electrical schematics, photographic image inspection, forensic evidence, or failure analysis.

Farthest Viewer
Whatever display technology you’re using it is important that everyone on the room can see and understand the information being shared. System design should take into account the viewer seated the furthest away from the screen.

AV designers used to take this measurement and multiply it by 4 (critical viewing), 6 (presentations), or 8 (standard video) to determine the image height. This simple rule of thumb does work for most applications, but for the best outcome there are a couple of more steps to follow.

Percentage Element Height
For BDM you should also take into account the size of elements such as words and graphics. This is the percentage of the image height that text will be and is expressed as percentage element height (%EM). This percentage depends on the type of content, but most designers use %EH between 2% and 2.5%.

Height Above Finished Floor
Most designers prefer the bottom of the image to be at least 48” above the finished floor in commercial applications. This allows for unobstructed views from further back in the space. This also means there is a a set amount of space for image height, black drop, and the screen case or screen frame. If there isn’t enough room, you might need to compromise of screen size or consider using multiple displays in the space.

Viewing Category Calculations
Once you have the above data in hand it’s time to bring it all together and calculate your screen size. There are separate calculations for BDM and ADM. Use the relevant equation show here to determine your optimum image size!

How About a Shortcut?
If you’d rather not do all that math, Draper has you covered! You can simply use our free online Projection Planner 2.0! Just enter the measurements discussed above and let the planner do the work!

You can also then continue on through the planner to get the best viewing surface based on projector specifications, ambient light, and more. Click here to use the powerful and free Projector Planner 2.0.