Projector Calculators
Projector throw distance.
Enter the image width you want and the projector throw ratio, or the low and high ends of its zoom range, to see how far from the screen the lens should sit. Use the ratio from the spec sheet. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Worked example
For a 100 in wide image with a 1.4 to 1.6 zoom lens: nearest distance = 100 x 1.4 = 140 in (11.7 ft) and farthest = 100 x 1.6 = 160 in (13.3 ft). A fixed 1.4:1 lens needs exactly 140 in.
How it works
From the throw ratio definition in the Throw (projector) - Wikipedia article (distance to the screen divided by the width of the screen), throw distance = image width x throw ratio. A zoom lens that lists 1.4 to 1.6 can sit anywhere in the resulting range and still fill the same width.
This is a geometry estimate, not a substitute for the manufacturer throw table in the projector manual.
Sources: Throw (projector) - Wikipedia. Each opened 2026-10-08.
Planning guide only, not professional advice. Figures are estimates from the inputs you enter.
FAQ
How far should a projector be from the screen?
Multiply the image width by the throw ratio. For a 100 in wide image and a 1.4:1 lens that is 140 in, or 11.7 ft.
Is the throw ratio based on width or diagonal?
Width. If you only know the diagonal, convert it with the screen width and height calculator first.
What do short throw and long throw mean?
They describe the throw ratio. A smaller ratio means the projector can sit closer for the same width.
Can I use any zoom setting?
Within the lens range, yes. 1.4 to 1.6 at 100 in wide gives 140 to 160 in of distance.