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How to Determine the Ideal Display Size (Based on the Size of a Room)

300 389 Core Innovations Group

Your classroom’s display has a larger effect on student outcomes than you may realise. This article examines how to use the size of your room to figure out the right display size.

Many studies highlight how large class sizes can negatively affect student outcomes.

Dr. David Zyngier compiled a report based on over 100 studies into the subject. He found that reducing class sizes leads to long-lasting educational benefits.

Many of these studies focus on the increased interaction between teacher and student as the reason for this improvement.

Unfortunately, reducing class sizes is often not an option. There are greater demands on the educational system than ever before. Teachers find themselves teaching large classes every year.

Many take advantage of modern technology, such as display screens, to convey information to large classes. However, it’s important to understand that display size has an effect on educational outcomes. This stands to reason. Students who can’t see the content on a display can’t learn from it.

This raises the question of how to choose the ideal display size.

Epson conducted a study into this very issue. Here’s what they discovered.

The In-Depth Study

A study from Radius Research highlighted the screen size issue. They collected 106 students and taught them in a 30-foot by 30-foot room. The study asked the students to copy six pieces of information from a 70-inch screen. This screen used a 4K resolution, which meant that blurriness and lack of clarity would not be an issue.

58% of the students copied at least one piece of information wrong.

In a class of 30, that means that 17 students don’t get the best educational experience possible.

This may be a shocking revelation to many teachers. A 70-inch screen is by no means a small display. Nevertheless, the study reveals that it isn’t adequate for the average classroom.

Now, consider these mistakes stretched out over an entire school year. Even getting one wrong piece of information out of every six shared could have a drastic effect on student outcomes. Many students will find themselves studying incorrect information through no fault of their own.

The obvious solution for many may be to offer printouts of the information shown on screen. While this resolves the issue, it may also create less engaging classroom sessions. Students will have to check their notes constantly to confirm what they can’t quite see on the screen. This takes their attention away from their teachers, which means they may miss some supplementary materials.

Furthermore, having printouts discourages students from taking their own notes. Several studies show that taking high-quality notes aids in recall. Students may not feel the need to do this if they have the printouts in front of them.

Due to this, it may be best to install a display that overcomes the issues that Radius’ study discovered.

The 4/6/8 Solution

Epson saw the results of Radius’ study and conducted further research of their own.

They discovered that using the 4/6/8 rule can help you to overcome the display size issue.

AV professionals often use the 4/6/8 rule to help them determine the best display sizes for classrooms.

It determines the display size based on the viewer who’s furthest away from the screen. Under the rule, the display’s height must be 1/4, 1/6, or 1/8 of the distance from the screen to the furthest viewer.

The height you choose depends on the content viewed:

  • 1/4 works best for inspections. For example, when looking at art or maps.
  • 1/6 works best for more detailed content. This could include slideshows and presentations where students need to read text.
  • 1/8 works for more general viewing. For example, watching video content that does not include small characters.

Once you’ve figured out the ideal height, you need to work out the right width for the screen. There’s an added wrinkle here. You have to figure out if the content you display is in 16:9 or 4:3 aspect ratio.

Let’s assume that you’re displaying in 16:9, which is the standard in today’s industry.

For that, you need to use the following formula.

16 x screen height = Z

Z / 9 = screen width

That leaves you with an ideal width based on the screen’s height.

You can simply replace the 16 and 9 used in the formula if you’re displaying at a 4:3 aspect ratio.

That leaves the formula looking like this:

4 x screen height = Z

Z / 3= screen width

What Epson Found

Epson applied the 4/6/8 rule to the display size conundrum that Radius highlighted.

Using this rule, they selected a display for a classroom and predicted that it would be able to reach 12 people. The results showed that it would actually reach 13.

As a result, we know the 4/6/8 rule can be an effective way to settle the display size debate.

Tips for Choosing a Display Size

The 4/6/8 rule ensures maximum coverage in the classroom. However, it’s also not the only way to help you choose a display size. There are several other things to take into account.

The DEV Rule

It’s not always appropriate to use the 4/6/8 rule when determining display size. And Epson’s whitepaper points to the Desktop Equivalent Visibility (DEV) as an alternative.

DEV compares the classroom viewing experience to the desktop monitor experience. This works on the basic principle that the ideal distance for a desktop display is arm’s length. This translates to between 20 and 30 inches, depending on the monitor size.

This uses the Snellen Eye Chart’s principle of 20/20 vision when scaled up.

The Epson whitepaper goes into much more detail about this technique. But the basic principle is that a character on the screen needs to double in size if you move twice the distance away from it.

Assume you achieve 20/20 vision of a character on a screen from 20 feet. That means you need to double the character’s size if the person moves 40 feet away from the screen.

Using this basic principle allows you to determine screen size using the DEV rule.

The Room’s Size and Usage

How do you determine which of the rules to use for determining your ideal display size?

Epson looked into this in their whitepaper as well. The general rule is that DEV works best for smaller rooms, whereas 4/6/8 works better for larger rooms.

They note that DEV works well for:

  • Huddle spaces
  • Medium-sized conference rooms
  • Small conference rooms

4/6/8 is the better rule for the following:

  • Training rooms
  • Large conference rooms
  • Classrooms

Using the wrong measurement technique for the room could lead to you choosing an inadequate display size.


Display size matters when it comes to teaching and training. It’s a crucial consideration for ensuring you deliver the best possible educational experience to students.

Radius’ study found just how extensive the effects can be. In the average 30-person classroom, an inadequate display negatively affects over half of students.

Use the information in this article to determine the ideal display size for your space.

Then, come to Core Innovation Group to discuss the issue in more detail. We install a wide range of Large Screen Technologies to ensure you deliver the best experience to your students.

Contact one of our representatives today. We’ll discuss your service requirements and provide you with a free evaluation of your current equipment.