Well, thanks to the good folks at Screen Innovations, there is a very helpful online tool to determine just that! The SI Seating Distance Calculator is a simple two-step process that will help you determine the right screen size for your room. All you have to do is select the screen ratio from a drop down menu and then using a cool little drag feature (see image above) you pick your seating distance. Once you have done so, your screen size recommendations are listed by: THX Min Size, SMPTE size and THX Max Size.
How cool is that? Now you're ready to shop for the perfect screen.
Click here! for Screen Innovation's "Seating Distance Calculator".