Project Optional. Used for the PDF report header.
Screen
Projector and lens
Throw distance
Calculation mode
Results
Pick a projector to begin.
Configuration
Computed
Next steps
BRC (on-screen brightness): The delivered lumens computed here is the input BRC uses to compute on-screen brightness in cd/m² and ftL. Per ADR 013, the value transfers manually — copy it into BRC's "Delivered lumens" field.
BSC (porthole fit): If you need to verify the projector beam fits through a porthole at this throw distance, run BSC. Same projector + screen inputs.
How to read this
Why projector aspect ≠ screen aspect matters
Most 4K residential projectors have a 1.90 (4096×2160) native imager aspect. Most residential cinema screens are 1.78 (16:9) or 2.39 (scope). When these don't match, the projected image is a different shape than the screen, and one of two things happens:
- Fill-screen (cinema-typical): the image fully covers the screen, with the extra image extending beyond the screen edges. The overflow is hidden by masking, curtains, or surrounding architecture. The image is wider (or taller) than the screen — you need a longer throw distance than the screen width alone would suggest.
- Fit-within-screen (no overflow): the image stays inside the screen, leaving unilluminated bands on the screen's non-matching edge. The image is the size of the screen along one axis, but the screen has visible black bands on the other. The throw distance based on screen width alone leaves the screen partially dark.
The "Screen + image" drawing makes this visible: the screen is filled grey, the projected image is outlined in burgundy, and the overflow or underfill regions are highlighted. The "image fit" selector lets you switch between the two modes. The throw-ratio in the calculator's headline already accounts for this — it's measured against the image width, not the screen width.
The zoom curve
The lens's efficiency varies across its throw range. At the wide end (lower throw ratios), the lens delivers near 100% of the projector's rated lumens. At telephoto (higher throw ratios), vignetting reduces efficiency — typically dropping to 70–85%. The vertical marker shows where your configuration sits on the curve.
The four modes
Mode A is the default — you have a throw distance and want to verify coverage + see delivered lumens. Mode B finds the throw distance that delivers a target lumens value. Mode C shows the screen-width range the lens supports at a fixed throw distance. Mode D ranks all lenses compatible with the projector by delivered lumens at your geometry.