To determine the best seat-to-screen distance for a projection screen or HDTV in a dedicated home theater, THX recommends dividing the diagonal screen by .84. For example, an HDTV display with a 65-inch screen divided by .84 equals a 77-inch viewing distance (6.5 feet).
If your HDTV is going in a living room with limited space, THX recommends the following set-up:
35 inch class TV = 3.5-5 feet away
40 inch class TV = 4-6 feet away
50 inch class TV = 5-7.5 feet away
60 inch class TV = 6-9 feet way
It might seem that THX is recommending a very large screen size for your room. But, it’s important to note two things: 1) THX screen size recommendations are based on recreating an immersive cinematic experience in your living room or home theater, and 2) the biggest consumer complaint about HDTV purchases is that they wish they had gone bigger.
You will also want to make sure that each viewer has a clear site line to the display. Try not to place the display too high on the wall - viewers should not have to look up more than 15°.
