Before choosing the size of your projection screen, make sure that your projector has sufficient luminance and throw distance for the screen size you need.
Luminance is your projector’s brightness and throw distance measures the space between your projector’s lens and the screen itself. As long as your projector has sufficient brightness, choosing the right screen size is easy.
Society for Motion Picture & Television Engineers (SMPTE) recommends that the minimum viewing angle (from your eyes to the edge of the screen) is 30°. This is the rule for movie theaters and it has been adopted for home theater to achieve an adequate degree of immersion. Based on SMPTE standards, here is an easy guideline to follow: