The Projector Brightness Calculator below is used to calculate how bright a projector you need
according to a given screen and a specific desire for quality. The calculator enables you to compare
two different setups - e.g. different size, different image quality, different light scenario etc.

All grey fields must have a numeric value.
Image brightness needed based on best estimates:
Scenario 1
Scenario 2
ALRAmbient brightness level in the room
0-20 Dark room
200-300 Living room, Hotel, Airport, Bank, Auditorium, Conference room
400-500 Office Environment, Shop, Control room
1K-5K Daylight
50K-100K Direct sunlight
0-2 Dark room
20-30 Living room, Hotel, Airport, Bank, Auditorium, Conference room
40-50 Office Environment, Shop, Control room
100-500 Daylight
5K-10K Direct sunlight
LUX
ft-c
LUX
ft-c
ALSAmbient brightness level on the screen surface
Rule of thumb:
The light level on the screen is approx. 50% of the light level in the room
LUX
ft-c
LUX
ft-c
SRFScreen reflectance factor
Rear projection screens
0.9% Alpha
1.0% Zenith
1.3% GWA
1.7% NWA

Supernova screens
5% Typical ambient light conditions
8% Significant sidelight conditions
11% Sidelight only conditions

Standard white front projection screen 25%
%
%
%
%
ICRContrast level needed in final image
Not possible to achieve higher contrast ratio than the projector can provide. Reduce the requirement or increase the projector checkerboard contrast ratio
7:1 Passive viewing
15:1 Basic decision making
50:1 Analytical decision making
80:1 Full motion video
:1
:1
:1
:1
CProjector checkerboard contrast
60:1 Fair
80:1 Good
100:1 Very good
150:1 Great
200:1 Excellent
:1
:1
:1
:1
RAmbient light reflected back to the audience
NIT
ft-L
NIT
ft-L
BImage brightness needed based on best estimates
NIT
ft-L
NIT
ft-L
BmaxMaximum brightness allowed to be "eye-gonomical"
NIT
ft-L
NIT
ft-L
Projector brightness needed for the actual screen size:
Scenario 1
Scenario 2
Image height
mm
in
mm
in
Image width
mm
in
mm
in
Image area
m2
ft2
m2
ft2
Peak gain
Peak gain for rear projection screens
2.2 Zenith
2.3 Alpha
3.0 GWA
3.5 NWA

Peak gain for front projection screens
0.8 Supernova 08-85
2.3 Supernova 23-23
1.0 Standard white screen
Gain effeciency for horizontal viewing position
Horizontal viewing angle* 15° 30° 45° 60°
Alpha screen 100% 65% 26% 9% 4%
Zenith screen 100% 77% 30% 14% 11%
GWA/NWA screen 100% 94% 57% 36% 9%
Supernova 08-85 100% 89% 80% 73% 65%
Supernova 23-23 100% 67% 43% 32% 27%
Standard white screens 100% 98% 96% 94% 92%

*) O degrees is on-axis, perpendicular to the screen center

%
%
%
%
Gain effeciency for vertical viewing position
Vertical viewing angle* 15° 30° 45° 60°
Alpha screen 100% 65% 26% 9% 4%
Zenith screen 100% 36% 9% 7% 5%
GWA/NWA screen 100% 23% 9% 7% 6%
Supernova 08-85 100% 69% 20% 6% 2%
Supernova 23-23 100% 46% 10% 2% 1%
Standard white screens 100% 98% 96% 94% 92%

*) O degrees is on-axis, perpendicular to the screen center

%
%
%
%
Effective gain in viewing position
PBNEffective (net) projector brightness needed
lum
lum
lum
lum
Dimensioning the projector(s):
Scenario 1
Scenario 2
Loss for start-up adjustment of colours
Projector manufacturers often optimize for brightness and not for correct color reproduction.
Articles claim 15-20% average loss in brightness for calibration
1-chip projectors claimed to loose 20-40% brightness for calibration
3-chip projectors claimed to loose 5-15% brightness for calibration
%
%
%
%
Number of projectors
ea
ea
Blending zone
Hard-edge blending = 0%
Soft-edge blending = 10-25%
Stacked projectors = 100%
%
%
%
%
Lamp efficiency
Definition of lamp life = working hours until 50% effeciency.
75% is about average in lamp life
%
%
%
%
Brightness need adjusted for start-up adjustment of coulours
lum
lum
lum
lum
Brightness need adjusted for loss for edgeblending
lum
lum
lum
lum
Brightness need adjusted for loss due to lamp decay
lum
lum
lum
lum
PBGSpecified (gross) projector brightness needed
lum
lum
lum
lum
Scenario 1
Scenario 2