Projector Throw Calculator
How far should your projector be from the screen?
Calculate projector throw distance from screen size, or image size from distance, for any throw ratio and aspect ratio. Includes brightness estimates.
How it works
The math behind the answer
Every projector has a throw ratio: the distance from the lens to the screen divided by the width of the image it produces. A 1.5 throw ratio makes a 100 inch wide image from 150 inches away. Zoom lenses have a range of ratios; fixed and ultra short throw lenses have one.
Give the tool your screen size and it returns the range of mounting distances that will fill it. Give it a distance instead and it returns the range of image sizes you can achieve there. Aspect ratio matters because a 2.35:1 scope screen of the same diagonal is wider than a 16:9 one.
The brightness table converts screen area and gain into the lumens needed for standard on-screen brightness targets, so you can sanity check whether a projector is bright enough for your screen.
Common questions
- How do I find my projector's throw ratio?
- It is on the spec sheet, usually as a range like 1.32 to 2.15:1. Manufacturer websites also provide throw calculators for specific models.
- What screen size can I get from 12 feet away?
- It depends on the lens. A standard 1.3 to 2.0 zoom lens at 144 inches gives an image between about 72 and 111 inches wide, or 83 to 127 inches diagonal in 16:9.
- How many lumens do I need?
- For a 120 inch 16:9 screen with 1.0 gain in a dark room, about 700 lumens reaches the 16 foot-lambert reference. Aim higher for HDR or any ambient light, and remember real output is usually below the rated figure.