Go for 'Golden Ratio' that is 1:1.618:1.618 (H:W:L). Means if your ceiling height is (say) 9 feet then width should be: 9 x 1.618 = 14.562 feet and length should be: 14.562 x 1.618 = 23.56 feet.

The national average range for installing a home movie theater is between $20,000 and $70,000. Most people pay around $50,000 to convert a basement room into a dedicated home theater with carpeting, risers, seats, acoustic materials, and a full sound and visual setup.

Choose a room that's at least 15 feet wide and 20 feet long and you should have a good basis to start building your home theater. You may be a bit cramped if you opt to go smaller than this minimum home theater room size.

The ideal space for a home theater is 20 feet long by 13 feet wide and relatively isolated from the rest of the house. "It has to be in a place that does not interrupt the business of the home," says Rob Rickel, president of RSR Custom Renovations and Additions. "You don't want the sound disturbing everyone."