Direct answer
The correct screen size is the largest image that remains comfortable and fully visible from every important seat after accounting for viewing distance, content type, projector brightness, room light, speaker placement, and sightlines. Start with the seating plan and a desired horizontal field of view, then confirm that the front row is not forced to scan the image and the back row can still resolve meaningful detail. Screen height can also be limited by the center speaker, riser geometry, ceiling, and whether a constant-height CinemaScope system is planned. An acoustically transparent screen can place speakers behind the image, but it adds material, brightness, and installation considerations.
A professional design should draw the sightlines and mock up the proposed image before construction. The current AVIXA published-standards catalog and CEDIA/CTA RP22 provide useful performance-based frameworks.
Sources and technical references
Use the organizations responsible for a product, platform or standard to confirm current specifications and compatibility.
How this answer was prepared
Camelback Smart Homes publishes this FAQ library for homeowners, design professionals, builders and property teams comparing integrated technology. Answers begin with the practical conclusion, then explain the factors that can change it.
Limitations: This is general educational information, not a site-specific design, quote, code determination or compatibility guarantee. Final requirements depend on the property, construction, infrastructure, equipment versions and project goals.