As you see by the responses, there is no "too small" or "too big." You've got to work with what you have in spare square footage in your home. If you're building from scratch and you have no cost or property size constraints, then go with the larger dimensions that you have from Art & Jeff above. But, if you only hav limited space, that is fine too. As long-can fit a nice little theater in it. Anything larger is icing on the cake. You do want to consider what type of crowds you have. I'm in Philadelphia area, and my 13 x17 theater w/ 105" hd picture was a hot ticket for the Eagles this season (short of the stadium itself). We tightly but comfortably fit 9 with some extra seating on the floor in video game type beanbag seats. Would I have loved to have 16 or 18...sure! But my house came with a 13x17' living room, so that is what my theater size is. Maybe some day I'll convert the basement, but for other than the rare times I need large amounts of seating, my ht size is perfect for me, Mrs., and my kids. If someone offered to pay for and build me a 17x25 (or larger) addition to house a larger theater, I'll be happy to take them up on it. But I'm not waiting till that happens to enjoy the theater I have now.