Screens & Sizes

Notes

• Two different limits meet here, and most size charts only show one. The viewing angle decides how immersive the picture is: SMPTE puts the cinema reference at 30° of horizontal field of view, THX at 40°. Resolution decides how close you can sit before the picture stops looking like a picture and starts looking like pixels — about 1.6× the diagonal on 1080p, 0.8× on 4K, and 0.4× on 8K. At 14 feet, the viewing angle is the binding constraint — 4K resolution comfortably supports a screen up to 210 inches.
• This is why 4K changed the advice and 8K mostly has not. The old rule of sitting two to three diagonals back came from 1080p, where sitting closer showed the pixel grid. At 4K you can sit at roughly 0.8 diagonals with no visible structure, which is why the same room now takes a screen roughly twice the area. At 8K the limit moves again, but by then the viewing angle has become the constraint, and a screen big enough to exploit 8K at normal living-room distances is larger than most walls.
• Measure to where you actually sit, not to the middle of the room. The distance that matters is from the screen to the front of your eyes in your usual seat. On a sofa against a wall that is often a foot or two further than people estimate, and the recommendation moves by a whole size class.
• Bigger is the more common regret in the other direction. Surveys of home cinema owners consistently find the most frequent complaint is having bought too small, not too large. The practical brake is not the picture but the wall: measure the width you have, remembering a 98-inch 16:9 screen is about 85.4 inches wide before the bezel and stand.