How Do I Calculate Screen Size and Seating Distance for My Home Theater?
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My new house construction will include a theater room with 15-foot wide X 24-foot long dimensions (with a 9-foot ceiling). I am going to try to fit two rows of theater chairs (either with five chairs per row, or possibly four in the front row, and six in the back row). So, based on that information, can you please give me your suggestions for my projection screen size, distance from screen to the first row, and then the suggested distance between front and back row? Thank you in advance, for any and all advice.
Joe, the first thing to do is figure out where the seats will actually be placed in the room. I would put about 18 inches to 24 inches between the back row of seating and the front row of seating while those chairs are reclined to allow for clearance. Assuming the front row is about 12 feet from the screen and the back row is another five feet further away, that gives us 12 feet and 17 feet for the seating locations.
Screen size is often considered as a measurement of viewing angle, but more often it’s measured as a diagonal with an assumption of a 16:9 (1.78), HDTV format, projection screen. I won’t discuss the merits of the wider aspect ratios, such as 2.35 at this time, but will leave that open for another Q&A. The center of your typical movie theater often has seating that is about 1.5x the screen width away from the screen. In home theater, that’s about 9 inches of screen diagonal for each foot of viewing distance.
Now, for a single row of theater seating, the math would be easy. 9 inches x 12 feet, would be about a 108-inch diagonal screen.
Except, most people like sitting a little closer than the center row of their local cinema, and movies are often presented in the 2.35 aspect ratio, which makes them need a bit more width to create the same immersive experience. As such, in informal polls online, enthusiasts have overwhelmingly been choosing a screen size with a diagonal of between 10 inches- to 12 inches-per-foot of viewing distance. Some go larger. Some go much larger. A minority choose to go smaller.
What this means is that personal preference needs to come into play and you need to pick the seats in your home theater that you will consider your primary seating, and then pick a screen size which is appropriate for you and your family. With one caveat..which we will get to in a bit.
If your family likes being near the center of the theater, then choose a screen size which has about 10 inches of diagonal for each foot of viewing distance. That's about 120-inch diagonal for a 12 foot viewing distance. If the rear seats are at 17 feet and the front at 12 feet, then I would look for a compromise between 120 inches and 170 inches in diagonal. That might likely be at 133 inches to 150 inches diagonal.
While there isn’t one perfect size when there are two rows of seating, there are always seats which will be more immersive (closer) and those less immersive. A home theater is typically too small to get a perfectly sized screen for both rows of seating, but the immersion and quality can be outstanding regardless of the size chosen.
Now, as screen size gets larger, especially in the 150-inch or larger diagonal range, it will be important to watch how bright the projector is, and how much gain the screen has to help boost the brightness. As well, a dark theater with dark walls, ceiling, and carpet will improve upon overall performance greatly.
As for that previously mentioned caveat…if at all possible, buy your projector first and try out different sizes on your wall before you decide upon a specific screen size. Overwhelmingly, this is the recommended course of action for people who are new to projectors or who have more difficult setups—even if that means borrowing a projector for a few days to just give it a try. The ability to hook up a laptop or disc player and just watch a movie, sitting in a lawn chair at the same distance from the screen, with an image on your wall at some different sizes, can help you understand the difference between 12 inches of diagonal per foot of viewing distance and 10 inches of diagonal. It allows you to move the chair around and get a very real feel for what you like.
I know my preference is for about 10 inches of diagonal per foot of viewing distance, but I have installed setups in which people are happy with as much as 14 inches of diagonal for each foot of viewing distance.
Paul Vail has been a professional audiovisual engineer since 1999. He works day-to-day for a commercial integrator and runs his own residential installation company, AV Integrated, out of Chantilly, VA, covering the greater Washington D.C. area. He has been the moderator of the ProjectorCentral Big Screen Forums from their inception more than ten years ago and has installed hundreds of projectors over the years, from entry level basement setups to 4K simulation systems using the latest in 3-chip DLP technology. He enjoys helping others learn about how to get the most value for their money, and setting realistic expectations and goals for the setup they are working toward. You can submit your question for Paul and ProjectorCentral Q&A by clicking here.