Buying a new TV is always exiting but many of our customers ask what size TV should they buy. Well there are two constrains in buying a TV. First is your budget and then is the size of the room or space that you will be watching your new TV in.

In order to understand how our vision works we need to see the following drawing that was created by Steven M. LaValle. Professor at the University of Illinois and Virtual Reality Chief Scientist for Huawei Technologies.

As you can see the “Preferred Viewing Area”is 15 degrees from center, both directions, so your eyes do not have to move from side to side to watch an object. After 15 degrees your eyes have to yaw right or left to see, with a maximum eye movement of up to 35 degrees. After that you have to also turn you head to see etc. We therefore are interested to find the size of the TV that fits in the “Preferred Viewing Area” .

In the fig 1 above the red line represents the TV and the blue line the viewing distance. On the ABC triangle we have half of the horizontal size of the TV(AC) the Viewing Distance (BC) and an angle of 15 degrees. Therefore we can compute the TV size given the Viewing Distance and vise versa with the following formula:

tan(15)=AC/CB where AC=(TVSize/2)*0.87 or TVSize*0.44 in inches,
CB=Viewing Distance in inches and tan(15 degrees)=0.27 or simply:
TV Size should be =60% of Viewing Distance

So pick up a measuring tape and measure the distance between your couch and where you want to place your new TV. Then multiply the measured distance with 0.60 and that should give you the maximum size of a TV you can buy.

An adjustment of 0.87 had to be made because TV sizes are measured diagonally and given in inches with a ratio of 16 horizontally to 9 vertically (16:9). Using the Pythagorean theorem we find that the horizontal TV distance is 87% of the TV size . So the horizontal size of a 50in TV is 43.5in (50*0.87)