Screen Size, Viewing Distance & Resolution

Before choosing a TV or movie projector for your home theater, it’s essential to consider your screen size, viewing distance, and resolution. Most people think the bigger the screen the better, but factors such as viewing distance, field of view, and resolution also have an impact on your overall experience.

Viewing distance: how far away from the screen you are sitting
Field of view: viewing angle; how immersive your experience feels
Resolution: the visible detail in the image, usually described in approximate horizontal pixels (e.g. 2K, 4K, 8K)

Some of these factors may already be decided for you based on the size or shape of the room. For example, if it’s a living room, you may already know your viewing distance based on how far your primary seating is from the location of your new TV or projector. If it’s a new theater build, you may have more flexibility.

Once you have an idea of how far away you’ll be sitting from the screen (viewing distance), you can decide on the appropriate screen size based on your desired field of view (more on this below). Then you can decide how much resolution is appropriate for a TV or projector in that space. While anyone would agree that more pixels are better, many people don’t take into consideration whether their eyes can actually resolve the higher resolution, based on how far away they are sitting from the screen and whether they have 20/20 vision (including vision corrected to 20/20).

The closer you are to a screen, the more likely you are to see pixel structure depending on the size of the pixels and the amount of space between them. The farther away you are, the less likely you are to notice whether the display you’re watching has 4K, 2K, or even SD resolution.

To figure out which TV or projector is appropriate for your space, we’ve created a guide to help break down the complexity.

For our purposes, the field of view is how much of your vision is taken up by the screen, and it’s measured by the viewing angle. The closer you are to the screen, the wider your viewing angle, and more of the screen will occupy your field of view. The farther you are away from the screen, the narrower your viewing angle, and less of the screen will occupy your field of view.

The recommended field of view from the Society of Motion Picture and Television Engineers (SMPTE) is 30°, whereas THX recommends a viewing angle of approximately 40° for an immersive, cinematic experience. Often the “sweet spot” in a theater will be placed at a distance away from the screen so that the field of view is optimized at this 40° viewing angle. In other rooms, such as a great room or multipurpose room, it’s more common for the field of view to be closer to 30° given its mixed usage.

According to THX, the general rule of thumb for a cinematic experience (40° field of view) is to multiply your viewing distance (in inches) by 0.835 to determine your appropriate screen size (in diagonal inches). For mixed viewing (30° field of view), you’d multiply your viewing distance (in inches) by 0.65.

Immersive experience (40° field of view)
Viewing Distance (inches) x 0.835 = Screen Size (inches)

Mixed viewing (30° field of view)
Viewing Distance (inches) x 0.65 = Screen Size (inches)

Let’s say your couch is 7 feet away from the wall where you’re planning to mount your TV or projector. Based on the calculations below, you’d want a 70” screen for a more immersive, cinematic experience, or a 55” screen for more of a mixed entertainment space.

Immersive experience (40° field of view)
Viewing distance = 7 feet (84 inches)
84 x 0.835 = 70” screen

Mixed viewing (30° field of view)
Viewing distance = 7 feet (84 inches)
84 x 0.65 = 55” screen

Generally speaking, you could go with a size in between those two and likely be happy. If you go bigger, the screen may feel uncomfortably large, and anything smaller may feel just too small.

Most TVs and projectors are currently available in 4K resolution, but some are still 1080p (HD, 2K), and more and more are becoming available in 8K. Do you want to future-proof your room with 8K? Is 4K the way to go because that’s what everyone else is buying? How do you choose?

Here is a graph that breaks down the typical resolutions, screen sizes, and viewing distances to help you determine which resolution is appropriate for your screen size and viewing distance. (This chart assumes 20/20 vision, or vision corrected to 20/20.)

From our example earlier, with a screen size of 70” and a viewing distance of 7 feet, a 4K display is appropriate for your needs. If you went with 8K, it is very unlikely you would notice a difference in quality (unless you walked up to the screen and stood 4 feet away). If you chose a 2K screen, you would likely see some pixel structure, and things would look visibly lower resolution. If instead, you went with the 55” screen at 7 feet away, you’d be on the border between 2K and 4K.

If you are on the border between two resolutions, it would likely be worth bumping up to the higher resolution TV or projector.

We recommend a field of view of 30° to 40°, depending on whether your room is intended for casual viewing or an immersive experience. While most manufacturers are producing TVs and projectors in 4K resolution, more options are becoming available in 8K, and there may still be options for 2K (1080p, HD). Determining the right screen size for your space will depend on your field of view, viewing distance, and resolution.

One more thing to keep in mind is availability of content. While more and more movies and TV series are being released in 4K resolution, and very little content is available in 8K, as long as you are beyond the 30 degree viewing angle distance, 2K content – which makes up the majority of available content – will look perfectly fine. Generally speaking, 2K is great at SMPTE 30°, and 4K is worth it at THX 40°.

For further research, we recommend the following:
• TV Size to Distance Calculator
• Reference Viewing Environment for Evaluation of HDTV Images
• Does 4K really make a difference?