Speaker Placement Calculators
This is a collection of speaker placement recommendations from around the web. All of these calculations are based on proportions so use what ever unit of measurement you feel comfortable with. All Measurements are for from the front center of the speaker. Also, if it recommend speakers flying outside of your room you may not want to use that formula, try another one. These may work perfectly for you out of the box, but in most cases placement will still need tweaking to achieve good imaging and even bass response.
The Real Trap option is designed to provide the flattest bass response in some rooms. Originally devised for near field monitoring environments and can work well with some desktop setups.