Once you have decided to have a home theater, nothing will stop you! During your journey of creating your home theater, there are lots of decisions you have to make (which is a common theme of the home theater process). This includes lots about your screen – learning about viewing angles, screen choices, and how far away should your seats be from your screen.
In a prior post, we talked about viewing angles, and here we’ll get into where your seats go, and how you can figure out the correct viewing distances for your theater.
There are some formulas to figure out the recommended viewing angle limitations, but keep in mind that your own personal preference matters as well. Don’t focus solely on the math of these basic formulas, at the expense of ignoring what you personally like.
In other words, do you like to sit closer to a screen, and have that ‘bigger’ feel, or do you like to sit farther away from the screen? That matters as well, it isn’t just about the math.
But, It Is Easy Math!
OK, so onto the basic math here. Don’t worry, it isn’t going to be hard!
We’ll go through the main two formulas, starting with the SMPTE recommendation and then the THX recommendation.
The Society of Motion Picture and Television Engineers (SMPTE) define the farthest viewing angle at 30 degrees. To use this formula, and to create your viewing distance, you take the Screen Diagonal (in inches) divided by 0.6. The answer (also in inches) to that is your viewing distance, at a 30 degree viewing angle.
Let’s work through a common example, using a screen diagonal of 120 inches.
120 divided by 0.6 equals 200. 200 inches, divided by 12 is 16 feet, 8 inches. This means that, when following the SMPTE recommendation, your eyes should be 16 feet 8 inches away from a screen that is 120 inches diagonal, at the farthest seating position.
Now the THX recommendation ends up with you closer to the screen, and provides a more immersive experience. This originates from THX being for the commercial movie theater market, where the bigger screen experience is preferred.
The basic formula is the same, you start with your Screen Diagonal (in inches) size and you divide it. However, with the THX recommendation, you divide by 0.84, and your answer (in inches) is your viewing distance.
Let’s work through the same common example, a screen diagonal of 120 inches.
120 divided by 0.84 equals 143 (excluding the fractional remainder). 143 inches, divided by 12 is 11 feet, 11 inches, so just under 12 feet, and this would be the farthest recommended seating location.
You can see that with the SMPTE viewing angle, the seating is 16′ 8″ from the screen, and with the THX viewing angle, the seating is 11′ 11″ from the screen, that is already a pretty large range of where you should put your seats, so clearly there is room for flexibility here.
In interviews with THX, the discussion of an ‘ideal viewing angle’ comes up, and it is right around 50 degrees, on a scope screen, so if you are looking for a good starting point, you can begin there.
Forget Angles, Let’s Just Go With Height
The other way of calculating your viewing distance is using the height of the screen as your starting point.
The general consensus on the closest would be two times the screen height and the farthest being 4 times the screen height.
So back to our example screen. Let’s say you have a 2.39:1 ratio screen, that has a diagonal of 120 inches. That screen is 111 inches wide and 47 inches high.
That means that the closest you would want to sit, if using a 2 times image height, would be 7′ 10″ from the screen, and the farthest, if using a 4 times image height, would be 15′ 8″.
With THX recommending 50 degrees as the ideal viewing location, that is 2.4 times the image height.
If we stick with our 120 inch scope screen then, at 50 degrees, you would have your primary seating spot be 9′ 5″.
To illustrate all this, let’s look at a visual example. This is a large home theater, with a twenty foot width on the front wall, and a screen that is twelve feet wide.
The screen dimensions are 144″ wide and 60″ high.
If we take a look at this theater and three rows of seats, at 2x height, 3x height and 4x height, you can see that the seats are 10′, 15′, and 20′ from the screen, all based on the height of the screen.
Do What You Like
Here is a trick that I recommend to everyone who is trying to figure out the right seating distance for themselves, because even though we have formulas and specifications, at the end of the day it is your theater and you need it to be right for you….
Go buy a ticket to your favorite commercial movie theater. Get there early enough to pick any seat you desire. On the ceiling will be tiles, and those tiles will be 2 feet x 4 feet (or if square they are 2×2). Find your favorite seat and then look up.
Count the number of tiles from right over your head to the screen. That tells you how far from the screen you like to sit.
Do the same thing again, only this time count the tiles along the width of the screen. That tells you how wide the screen is.
You now know the exact ratio of how far away from the screen you like to sit, and you can replicate that same ratio in your home theater.
If you need to, go see a few movies and call it ‘research’. 🙂