Theater Calculators
Projector Brightness (Foot-Lamberts) Calculator
https://www.theatersizing.com/calculators/projector-brightness/
Estimate only — not a calibrated SPL meter, an acoustic report or an electrical design. Confirm with measurement.
Projector Brightness (Foot-Lamberts) Calculator
Foot-lamberts = lumens × gain / area in square feet. Cinema SDR sits near 14–16 fL; living-room HDR wants more. High gain helps and hurts viewing angle.
Inputs
Results
- Image area
- 3.95m²
- Foot-lamberts
- 58.8fL
- Nits
- 201.5cd/m²
Calculation method
fL = (Φ × G) / A_ft². Nits ≈ fL × 3.426. Area comes from width × height.
Exact formula
A_ft² = W·H·10.764. fL = lumens·gain / A_ft². Limits: centre-screen, no ANSI checkerboard, no lamp age, no HDR tone-map.
Frequently asked questions
How many foot-lamberts for HDR?
Consumer HDR highlights want far more than 16 fL. Treat this as SDR cinema math, then add headroom for HDR tone-mapping.
Does ALR lower fL?
On-axis gain can be near 1.0; off-axis it drops. This tool is on-axis only.
Lux or foot-lamberts?
Projectors are specified in lumens; screens in fL or nits. This converts between them.
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