Tool — Reference Calculators

Color & Light
Calculators

Convert between lumens and nits using your screen's physical dimensions, and translate between CIE xy chromaticity coordinates, correlated colour temperature, and Δuv — the numbers that define where your white point actually sits.

Lumens↔ Nits
xy↔ CCT + Duv
MethodRobertson 1968

Lumens ↔ Nits

SCREEN BRIGHTNESS CONVERTER
lm
inches
Formula: nits = lumens ÷ (area m² × π)
Area derived from diagonal and aspect ratio.
Result
 

Screen area
 

Context

xy ↔ CCT + Duv

CHROMATICITY CONVERTER — ROBERTSON 1968
x
y
Method: Robertson 1968 isotherms in CIE 1960 UCS.
Duv positive = above locus (greenish). Negative = below (pinkish).
Accurate ~1000K – 20 000K.
Correlated colour temperature
 

Duv
 
−0.02Planckian locus+0.02

CIE 1976 u′v′

Screen Size ↔ Seating Distance

VIEWING ANGLE CALCULATOR
ft m
THX: 36° — recommended minimum for cinema.
SMPTE: 30° — broadcast / mastering standard.
40°: Immersive viewing, ISF preference.
Angle = horizontal field of view subtended by screen.
SMPTE
30° horizontal
 
THX
36° horizontal
 
Immersive
40° horizontal
 
LUMENS → NITS

Enter lumens and screen size

Input your projector or display's lumen rating and your screen diagonal. The calculator derives the screen area and applies the photometric formula to give you surface brightness in cd/m².

xy → CCT

Enter your white point xy

Take the CIE x and y coordinates from your calibration software or colorimeter report. The calculator uses Robertson's 1968 isotherms to find the nearest correlated colour temperature and Duv — how far your white sits from the Planckian locus.

CCT → xy

Enter CCT and Duv

Reverse direction: give a target CCT and Duv to find the corresponding xy chromaticity. Useful for setting calibration targets or checking what xy your display should achieve for a given standard.

SCREEN SIZE

Enter distance or screen size

Enter your seating distance to find the recommended screen size per SMPTE (30°), THX (36°), and immersive (40°) standards — or work backwards from a screen size to find ideal seating distance.