Projector Brightness and Throw
The projector lumens a screen needs from its size, gain, and target foot-lamberts.
Example
You enter
- Screen width (ft) 16
- Screen height (ft) 9
- Screen gain 1
- Target foot-lamberts 16
- Throw ratio (optional) 1.5
You get
- Required lumens 2,304 ANSI lumens
- Screen area 144.0 sq ft
- Throw distance 24.0 ft
Checked against published worked examples from: ProjectorCentral (M. David Stone).
Details, formula, and sources
ScopeWith the throw distance from the throw ratio. The projection analog of lighting-beam's fixture photometry.
Formula or tableRequired lumens = target foot-lamberts x screen area / gain; throw distance = throw ratio x screen width.
Source and editionStandard AV screen-luminance identity (SMPTE-style targets, by name); foot-lamberts = lumens x gain / area.
Free accessScreen-luminance methods free at projector and screen maker technical pages.
What governsMath aid for personal verification. Stop work and consult the qualified person on site if any number does not match the field condition.
API field namesscreen_w_ft, screen_h_ft, screen_gain, target_foot_lamberts, throw_ratio, required_lumens, area_sqft, throw_distance_ft
- Target luminance band ~16 fL dark room, ~30-50 fL ambient (default 16, editable)SMPTE-style AV practice