Projection planning often starts with simple geometry: lens-to-screen distance divided by active image width gives a throw-ratio prompt, and active image width plus aspect ratio gives image height, diagonal, and area. Those numbers are useful for early layout conversations, but they do not select a projector, certify a lens, prove content readability, or approve a rigging or electrical plan.
The source-aware workflow keeps the local math separate from source-backed decisions. Manufacturer lens charts, AVIXA display-size and contrast standards, SMPTE luminance context, screen-product data, measured venue conditions, rigging points, power, cable paths, venue rules, and qualified review still control the real installation or event package.
Throw Ratio Is a Geometry Prompt
The local throw-ratio relationship is straightforward: TR = lens-to-screen distance / active image width. If a projector lens is 30 feet from the screen and the active image width is 15 feet, the local prompt is 2.0:1. The same relationship can screen image width at other distances by holding the ratio constant.
That prompt is not a manufacturer compatibility check. Actual fit depends on the selected projector model, current lens chart, zoom range, focus limits, lens shift, offset, keystone, warping, mounting orientation, screen location, and site measurements. A coarse label such as short throw or long throw is a planning label only.
Projection Throw Ratio & Lens Calculator
Calculate projector throw ratio, lens type, and screen brightness in foot-lamberts for AV installations.
Brightness Prompts Need Measurement Context
The local brightness prompt uses entered lumens, selected gain prompt, and active screen area to show foot-lamberts and cd/m2. This can help compare assumptions, but it is not a measured photometric result. Projector age, lamp or laser mode, measured light output, color light output, content, screen gain curve, hot spots, ambient light, and room reflectance can change the visible result.
AVIXA DISCAS is a display-size and viewing-position standard, AVIXA ISCR is an image-system contrast measurement standard, and SMPTE luminance context is tied to specific motion-picture projection conditions. A simple local fL prompt does not prove conformance to any of those sources.
Screen, Venue, and Safety Gaps
Screen gain is not a single universal field result. Product data, viewing cone, material type, ALR behavior, color neutrality, screen condition, screen size, audience angle, and projector angle all affect how the image looks. A gain prompt in a local tool is only a placeholder until the selected screen product and venue layout are reviewed.
Projection work can also create non-optical hazards. Overhead mounting, rigging points, projector weight, vibration, heat, ventilation, power, grounding, cable paths, laser-light exposure, fire/egress rules, venue requirements, and AHJ conditions must be handled outside the throw-ratio math.