The best size of your home theater is the one you already have. Usually you will design your home theater around the size of your room. Work with what you have. If you are building a house from the ground up you might want to consider this more precisely. Also you may be finishing off your attic or basement. Another option is adding an addition to your existing home.
New Construction
Either way your home theater will be met by certain limitations. If you are having a new home built builders generally offer home theaters as add-ons to the basic floor plan. Usually these are a predetermined foot print that fits in existing floor plan offers. Which brings us back to you work with what you have.
Remodeling
When finishing your attic or basement you will be faced with design challenges such as utilities and use of space. The size of your home theater is once again limited to fit with your existing foot print. Again this leads us to working with the space you have.
Additions
When building an addition you may be limited to building codes and property line set backs or just budget. Also design aspects of your addition may require a certain size home theater with respects to your existing layout. You want the addition to fit proportionally to the rest of the home. Again working with what you have.
One thing to consider is the bigger your home theater room the more you will need to spend. You will spend more on a bigger TV or screen, more on bigger speakers and more on an amp/receiver to push the bigger speakers.
Room Size
If you are looking for hard numbers 10ft x 12ft is a good size to start with. That is not a standard but it is just a place to start. You can go smaller than that and it will be just fine. In a 10ft x 12ft room you can seat 4 people comfortably. If you are really space deprived you can put your home theater in a 3ft x 4ft closet. Get a comfortable chair, a lap top, a mini table and a set of headphones. That will get you the quickest, quietest and least expensive home theater room any where.
If you are considering just using the TV as your equipment we can assume its not really a home theater. What makes a home theater is the separate sources of audio other than the on board speakers of your TV. The most basic step up would be a soundbar. A soundbar will serve a small room fine.
Home Theater Types
The next step would be a soundbar with sub woofer. Consider this setup for the next size up room.
Then you have the home theater in a box option. Home theaters in a box most likely have 3 to 6 speakers packaged with a receiver or a DVD/bluray player. This all depends on the manufacturer. This is a great option for those of you looking for something that sounds good at a good price with not to much hassle to install.
Then you have the custom type home theaters where you buy your components separately. This is where you can start spending much more than the simpler options but if your room is rather large you may need to get a more robust home theater.
All these options are interchangeable it all depends on your taste and budget. At the end of it all it will be you and your family spending the most time in your home theater so make it to your liking. Don’t worry about what others might think about it..