Projector Calculators
Projector image size from throw distance.
Enter how far the projector sits from the screen and its throw ratio, or the low and high ends of a zoom range, to see the image width, height and diagonal. Check the throw ratio on the projector spec sheet. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Worked example
A projector 10 ft (120 in) from the screen with a 1.4 to 1.6 zoom lens and a 16:9 image. At 1.4:1 the width is 120 / 1.4 = 85.7 in, so the height is 48.2 in and the diagonal 98.3 in. At 1.6:1 the width is 120 / 1.6 = 75.0 in and the diagonal 86.1 in.
How it works
The Throw (projector) - Wikipedia article defines throw ratio as the relationship between the distance to the screen and the width of the screen (assuming the image fills it). So image width = throw distance / throw ratio, and height follows from the aspect ratio. A zoom lens has a range such as 1.4 to 1.6, and the same distance gives a range of sizes.
This is a geometric estimate. Confirm with the throw table in the projector manual before mounting.
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 do I calculate projector screen size from distance?
Divide the throw distance by the throw ratio to get the image width, then use the aspect ratio for the height. At 120 in and 1.4:1 the width is 85.7 in.
What is a throw ratio?
It is the throw distance divided by the image width. A ratio of 1.4 means the projector sits 1.4 times the image width from the screen.
What does a range like 1.4 to 1.6 mean?
The lens zooms. At the same distance it can fill a screen from 75.0 to 85.7 in wide.
Does the aspect ratio change the width?
No. The throw ratio relates distance to width, so the aspect ratio only changes the height and diagonal.