Diagonal measurement × 2.5 (corresponding to 20-degree viewing angle)
One of the more popular recommendations on the proper HDTV viewing distance is multiply the diagonal measurement of the display screen by 2.5. This recommendation is cited by television manufacturers,[15] retailers,[16] respected publications[17][18] and websites,[19] though the popular electronics review website CNET suggests that high-resolution content can be watched at a closer distance – 1.5 times the display screen's diagonal measurement (corresponding to 32 degree viewing angle).[20]
Diagonal measurement × 1.6 (corresponding to 30-degree viewing angle)
Viewing an HDTV from a position where the display occupies a 30 degree field of view is widely quoted as the SMPTE (or SMPTE 30) recommendation (equivalent to about 1.6263 times the screen size in a 16:9 TV). This recommendation is very popular with the home theater enthusiast community,[21][22] appears in books on home theater design,[23] and is also supported by a white paper produced by Fujitsu.[24] Although an article on research into setting the specification for the next evolution of HDTV, Ultra HDTV (or UHDTV), does support the premise that HDTV was optimized for a view angle of 30 degrees,[10] there seems to be no direct recommendation from SMPTE on the issue.
Diagonal measurement × 1.2 (corresponding to 40-degree viewing angle)
THX recommends that the “best seat-to-screen distance” is one where the view angle approximates 40 degrees,[25] (the actual angle is 40.04 degrees).[3] Their recommendation was originally presented at the 2006 CES show, and was stated as being the theoretical maximum horizontal view angle, based on average human vision.[26] In the opinion of THX the location where the display is viewed at a 40 degree view angle provides the most “immersive cinematic experience”,[25] all other things considered. For consumer application of their recommendations, THX recommends dividing the diagonal screen measurement by .84 to calculate the optimum viewing distance, for a 1080p resolution. This equates to multiplying the diagonal measurement with about 1.2. [25]