Finding the right size TV for your room is easier than you might think. But picking the right resolution is just as important.
Written by Dennis Burger - Maybe it’s due to my job, maybe it’s fate, or maybe I’m just being punished for something my karma did in a last life—or however that works—but when my friends are in the market for a new TV, I’m always the first one they call. And the conversation invariably plays out the same way every time: “I just want to make sure I’m getting my money’s worth.” OK. “I want the best TV I can afford.” I love to hear it. “I don’t need anything as monstrous as yours, though!” Insert the sound of a phonograph needle being dragged quickly across vinyl right here and you’ll get the gist of how this scene will play when they film my life story.
My 56-in. Samsung DLP TV, I explain, falls right in the middle of THX’s acceptable range for my room size and eight-foot seating distance. In fact, it could actually stand to be a teensy bit bigger or I could benefit from sitting just a smidge closer. “I don’t care,” I hear time and time again. “I don’t like it that big….” Beat, one, two three. “I definitely want 1080p, though.” At this point, I’m thinking that cheesy, deflated “wah-wah-waahhh” musical sound effect of old would sum up the mood perfectly. Close-up on my bewildered face, and… cut. That’s a wrap.
All kidding aside, I seem to spend a lot of time explaining to my TV-shopping friends that they’re using two very contradictory criteria to look for their dream TV. Granted, no one should be forced to live with a screen they find overwhelming, but all the extra pixels in the world aren’t going to make a difference if the flat panel on the wall across the room looks like a postage stamp stuck to a manila envelope.
Both SMPTE (the Society of Motion Picture and Television Engineers, developers of those wonderful color bars we all know and love) and THX (developers of deliciously loud logos, among other things) have developed theatrical standards for screen size that work just as well for home theater. THX standards require the back row of seats to have a 26-degree or greater viewing angle, with a 36-degree viewing angle recommended for the optimal movie-watching experience. SMPTE nearly splits the difference, with a recommended minimum viewing angle of 30 degrees.
Put away the slide rule—we at Electronic House are here to make your life easier; not force you to do algebra. Here’s a quick and dirty guide to calculating optimal screen size for your room when purchasing a widescreen TV:
- Measure the distance from your seat to the empty spot you hope to fill with a new TV.
- If you measured in feet, multiply by 12. If you measured in inches, bravo! You’re one step ahead of me.
- Take 55% of that number and you have THX’s minimum recommended screen size in diagonal inches. Take 60% for SMPTE’s minimum recommended screen size, and 75% for THX’s recommended ideal. (Keep in mind, these numbers are a rough approximation of the SMPTE and THX guidelines, but given that TV’s only come in a finite number of discrete sizes, they’re better than close enough.)
For example, let’s assume you’ll be sitting 8 feet from your screen, like me. That’s 96 inches. So according to THX, you need a 52.8-inch set (96 x 0.55). You could probably cheat and get a 50-inch if you intend to watch lots of movies that keep you on the edge of your seat. To meet SMPTE specs, you would need 57.6 inches worth of diagonal screen real estate (96 x 0.60), so a 56- or 60-inch should fit the bill. And for the optimum movie-viewing experience, THX would suggest a 72-incher (96 x 0.75).
At that point and beyond, you would probably be better off with a full-fledged projection system. (In fact, THX has recently begun recommending a 40-degree field of view for dedicated home theaters with projections screens.) For our purposes—TV shopping, not dedicated home theater construction—let’s ignore the upper end of the spectrum. For my all-purpose media room, I find that sticking to the middle of the acceptable range—that is to say, going by SMPTE’s recommended 30-degree viewing angle, in effect splitting the difference between THX’s minimum and recommended screen sizes—gives me the best mix of movie-watching enjoyment and multi-purpose practicality. Anything bigger and legacy standard-definition material (OK, as long as we’re being honest, The Weather Channel) just becomes unwatchable; anything much smaller and the extra resolution of 1080p Blu-ray movies would be wasted on my eyes.
The human eye, at its best, can resolve about 1.25 lines of resolution or pixels per minute of arc. A minute is 1/60 of a degree. (Bear with me here for a minute; the math lesson is almost over, I assure you.) A 1080p set has 1920 pixels of horizontal resolution. So it doesn’t take much ciphering to figure out the field of view a 1080p display needs to take up if we’re going to be able to appreciate the detail. Dividing 1920 by 60 and again by 1.25, we find that at a viewing angle of less than 25.6 degrees, we’re wasting pixels. Why does that number sound familiar? Oh yeah! Those THX guys must be on to something!
So, for those of you who saw decimals and skipped to the end, or just wanted to get to the good stuff, if you’re buying a new TV—not a projector—for a multi-purpose media room or den, and want to find the size that best fits your room, delivers a good cinematic experience, and also works for watching the nightly news (or Stephanie Abrams, meow!), find a set whose horizontal screen size is about 55% to 60% of the distance from your seat to the screen. Within that range, you’ll still get the most out of that spiffy new 1080p set. If that’s still too big, there’s nothing wrong with buying a dainty little postage stamp TV, but you should definitely move down to a 720 display and save yourself a few coins. In fact, when viewing a 37-inch widescreen set from a distance of 8 feet, even 720p is arguably overkill. But try telling that to my friends!
Written by Dennis Burger
