Practical tools for measured work
Projector Screen Size from Room Calculator
Find the largest image that fits your lens distance, throw ratio and usable wall height.
The optical image fits within the entered wall height.
How it works
How to use it: enter usable lens distance, throw ratio, wall height, aspect ratio, lumens and screen gain. The tool finds the optical image and reduces it if the wall height is tighter.
Formula. Image width = throw distance / throw ratio. Diagonal comes from aspect geometry. Estimated foot-lamberts = lumens x gain / screen area in square feet.
Example. At 144 inches and 1.20 throw ratio, image width is 120 inches; a 16:9 image is about 137.7 inches diagonally before wall-height limits.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Available lens-to-screen distance
- 144 in
- Projector throw ratio
- 1.2
- Usable wall height
- 72 in
- Aspect width
- 16
- Aspect height
- 9
- Rated projector lumens
- 2000
- Screen gain
- 1
Primary result: Usable diagonal: 137.7 in.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
Rated lumens are not guaranteed calibrated lumens, and brightness changes with image mode, zoom, lamp age, ambient light and screen behavior. Check the projector's official zoom, lens-shift and installation limits.
Frequently asked questions
Why can wall height reduce diagonal?
The projected aspect ratio fixes width-to-height. If the calculated image is too tall, both dimensions must shrink together to avoid cropping.
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