So you want a new TV and you want a BIG one. Or at least a bigger one. How big is too big? What’s the optimum viewing distance? For optimum viewing you want to be close enough that you don’t have to squint but not so close that you can see the “pixels” in the image. So this means that you can sit closer to a HDTV than a regular TV it also means that to “fully” enjoy the higher quality picture of a DVD or HDTV picture you shouldn’t sit as far away.
Two rules of thumb are as follows:Rule #1: Determine the viewing distance from the TV. Mulitply the distance in feet by “x” to get TV size (diagonal) in inches. Multiply by 4 for Cable TV, 6 for Digital Cable/Satilite/DVD, 7 for HDTV.
And my preference, Rule #2: Measure the width of your TV screen. Optimum viewing distance for TV is 3-6 times this width and 1.5-3 times for DVD/HDTV. Since you have a nice overlap at 3x you can use it for the best all around viewing distance/TV size. Now since regular TV is 4:3 ratio you can use 3,4,5 triangle math and come up with the one simple rule: TV size (inches diagonal) divided by 5 gives you the optimum viewing distance in feet.
Now remember this is the optimum setting for you Home Theatre/Main TV. So while a 70″ projector image is perfect for a 14′ distance to the main couch in the living room… putting a 55″ screen for the 11′ across the bedroom is a tad overkill.