# Calculating size based on view distance?

Discussion in 'Displays' started by LowellG, Sep 7, 2003.

1. ### LowellG Stunt Coordinator

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I am trying to figure out what size widescreen TV to buy. I know I have seen some standard suggestions here, but in searching for them I couldn’t find them. There were basically some ratios that said if your view distance is X amount of feet, buy this size widescreen or this size 4x3. I also saw a weblink on one forum that had you punch in the screen size of your 16x9 or 4x3 TV and it calculated a 16x9 wide screen = a blank size 4x3 and visa versa. Does anybody know how to calculate that? I currently own a 32in 4x3 and don’t want to have a smaller 4x3 image when I go to widescreen. My current view distance is 10-12 feet if that helps. Thanks, Lowell.

2. ### Stephen Tu Screenwriter

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The rule of thumb to start with is view distance = 2x screen diagonal for a 16:9 screen. Then just go to the store and see for yourself on a variety of sources since people have differing preferences.

How to calculate - just remember Pythagorean theorem from geometry class, diagonal ^2 = width ^2 x height ^2. And triangles inscribed in sets with the same aspect ratio are "similar"; if you expand one dimension the other dimensions will expand at the same ratio. For 4:3 TVs, you have 4 width x 3 height and 5 diagonal. For 16:9 TVs, 16 width, 9 height, 18.36 diagonal.

To find equivalent 4:3 on a 16:9, equalize the height. To find the 16:9 image on a 4:3, equalize the width.

E.g. you have 32" 4:3. 32/5 * 3 = 19.2" screen height. 19.2/9 * 18.36 = 39.17", which is the diagonal measurement on a 16:9 you'd need to have the same size 4:3 image.

3. ### Craig Robertson Supporting Actor

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check out the seating distance calculator here.

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