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 2304 ANSI lumens
- Screen area 144.0 sq ft
- Throw distance 24.0 ft
Details, formula, and sources
With the throw distance from the throw ratio. The projection analog of lighting-beam's fixture photometry.
Required lumens = target foot-lamberts x screen area / gain; throw distance = throw ratio x screen width.
Standard AV screen-luminance identity (SMPTE-style targets, by name); foot-lamberts = lumens x gain / area.
Screen-luminance methods free at projector and screen maker technical pages.
Math aid for personal verification. Stop work and consult the qualified person on site if any number does not match the field condition.
Field names used by the API: screen_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