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Based on the SMPTE 30-degree viewing angle for the recommendation, THX 40 degrees for cinematic, and about 20 degrees as the comfortable minimum. With 4K content you can sit closer (or go bigger) than the old HD rules suggested without seeing pixels.
What The TV Size Calculator Works Out
- Recommended size: the diagonal that fills about 30 degrees of your vision, the SMPTE cinema standard, which works out at roughly 0.6 times the viewing distance. A typical UK sofa distance of 2.5 m points at about 62 inches, in practice the 55 to 65 inch classes; if the result lands between classes the consistent advice is to take the larger one.
- Cinematic / immersive: the THX 40 degree figure, about 0.84 times the distance, so the same 2.5 m room supports an 83 inch screen for a film-first setup.
- Comfortable minimum: about 0.42 times the distance (roughly 20 degrees); below this the set starts to feel small for films. 4K changed the old advice: pixels are invisible at half the distance HD needed, so the sit-far rules that produced 40 inch recommendations are obsolete, and buyers regret undersizing far more often than oversizing.
- Distance entered in (advanced): accept feet or centimetres instead of metres. Measure eye to screen from where you actually sit, not wall to wall.
- Viewing angle (advanced): override the 30 degree assumption. Sports and news viewers often prefer 26 to 28 degrees; gamers and film fans go to 35 or 40.
- Resolution and closest seat (advanced): the distance at which a person with 20/20 vision stops resolving individual pixels on the recommended size: about 1.1 m for a 55 inch 4K set but 2.2 m for the same size at 1080p, which is why 4K lets you sit closer or go bigger.
- The TV you are considering (advanced): enter a size to see the angle it fills from your seat, a verdict from "will feel small" to "very large", its ideal viewing distance and its width in centimetres.
- Width of the space (advanced): enter the alcove or TV unit width and a bezel-and-clearance allowance to get the largest diagonal and standard class that physically fits. A 65 inch TV is about 145 cm wide, which is the number that actually decides whether it fits the media unit.
- Size class table (advanced): width, viewing angle at your distance, ideal distance and a verdict for every standard class from 43 to 98 inches. Screen centre at seated eye level, about 1 m, matters as much as size; mounting high above a fireplace causes neck ache and washed-out viewing angles on many LCD panels.