How far away to mount your projector?
How big will your projection screen be?

 
Choose your projected display ratio:

Your Throw Ratio (check projector specs):

Distance from Projector to Wall:
ft.

Your diagonal projection size:
in. diag

 ↑
" high
↓
←
" wide
→

The Throw Ratio is literally the Distance from the projector to the wall, divided by the Width it displays the image.

Diagonal size (which is what TV's advertise) is dependent on the display ratio.

If you don't know your display ratio, it is probably Widescreen (16x9).

What this means is, Widescreen Width divided by 16 is equal to the Height divided by 9.

The average Throw Ratio is about 1.44, but it can range from 0.2 ("Ultra-Short Throw") to 2.0
Optimal viewing distance: 1.8 - 2.5 feet from screen.