Sizing a projected image
How you can achieve more readable, higher impact visuals

Sizing a projection screen can be a complex issue, but we always start with a very simple formula: the height of screen should equal the distance to the farthest viewer divided by six.

H = D/6

This is normally the ideal screen height when you’ll be showing computer text and you want it to be readable by everyone in the room. If you’re showing video only, you can get by with a little smaller screen; if you’re showing web pages with very small text, you may want to go a little larger. (Call us for advice when you get into these special situations.)

For a home theater where you want the highest visual impact, the screen height should be the distance to the best seat in your viewing area divided by 3.3.

H = D/3.3

The two formulas, by the way, are interrelated. If you size a screen for a room with many rows of seats using the first formula, you can find the best seat in the house by rewriting the second:

D = H x 3.3

Since there are several different screen formats available, to find the screen width, multiply the height times the aspect ratio of the screen you’ll be using. For a standard 4:3 screen, that’s H x 1.33. For wide-screen movies using a 16:9 screen, that’s H x 1.78. You can use this calculator:

 Distance to farthest viewer: Height: Width (4:3): Width (16:9):

Note these rules apply to TVs and flat-panel displays, though most often people use a TV smaller than the ideal. Of course, when that’s the case, it can be hard to read any computer text you may want to display.

Read more about seating considerations and determining the projector brightness you need

Our thanks to the late Kim Milliken of Da-Lite for working out these formulas.