Max Screen Size for a Projector
The largest screen a projector lights to a target brightness.
Example
You enter
- Projector brightness (ANSI lumens) 5000
- Screen gain 1
- Target foot-lamberts (16 dark, 30-50 lit) 16
- Aspect ratio width (e.g. 16) 16
- Aspect ratio height (e.g. 9) 9
You get
- Max screen area 312.5 sq ft
- Max width (ft) 23.57
- Max height (ft) 13.26
- Max screen diagonal 27.0 ft (325 in)
Checked against published worked examples from: ProjectorCentral (M. David Stone).
Details, formula, and sources
Scopemax area = lumens x gain / target foot-lamberts, then the width, height, and diagonal at the aspect ratio. A 5,000-lumen projector on a unity-gain screen at 16 fL tops out near a 27 ft (16:9) diagonal; a lit room at 30-50 fL shrinks it. Size the projector 20-30% over the minimum for lamp aging. Sizes the screen from the brightness budget, not the throw geometry; the room and the projector's lens range govern.
Formula or tableMax screen area = lumens x gain / target foot-lamberts; width = sqrt(area x aspect_w / aspect_h), height = width x aspect_h / aspect_w, diagonal = sqrt(width^2 + height^2).
Source and editionStandard AV screen-luminance identity (SMPTE-style targets, by name); foot-lamberts = lumens x gain / area, solved for the 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 namesavailable_lumens, screen_gain, target_foot_lamberts, aspect_w, aspect_h, max_area_sqft, max_width_ft, max_height_ft, max_diagonal_ft
- Target luminance band ~16 fL dark room, ~30-50 fL ambient (default 16, editable)SMPTE-style AV practice