RGB to CIE Color Coordinate Calculator
Convert sRGB or HEX colors to CIE XYZ, CIE 1931 xyY, and CIE 1976 u′v′ coordinates using a D65 white point. You can also enter xyY or u′v′ coordinates to calculate an sRGB preview, with relative Y or measured luminance in cd/m² or foot-lamberts.
Revision A-P15 · Circle, ellipse, box and polygon boundaries with calculated centroids; MIL-STD-3009 overlays updated . About FPD.DEV and its technical background.
How to use the calculator
- Start with your data: enter a HEX color or RGB values from 0 to 255, or enter CIE xyY or u′v′ coordinates.
- Choose the luminance scale for CIE input: use Relative Y for theoretical conversion, or select cd/m² or fL when entering measured luminance. RGB conversion returns relative Y.
- Calculate and record: use the button for your input format, then review the coordinates, luminance, and status. Use Copy Results or Print / Save PDF to retain the output.
The color swatch is an illustrative sRGB preview. It does not measure your display or reproduce a specified physical luminance.
Worked example: mid-gray sRGB to CIE coordinates
Enter R = 128, G = 128, B = 128 (HEX #808080) and select Calculate from RGB. With the calculator's sRGB/D65 assumptions, the displayed results are approximately:
- Linear RGB: 0.2159, 0.2159, 0.2159
- CIE 1931 xyY: x = 0.3127, y = 0.3290, relative Y = 0.2159
- CIE 1976 u′v′: u′ = 0.1978, v′ = 0.4683
The encoded value 128/255 is about 50.2%, but sRGB encoding is nonlinear. After linearization, the relative luminance is about 21.6% of the model's reference white. This is not a luminance measurement in cd/m².
For this example, each linear channel is calculated as ((128/255 + 0.055) / 1.055)2.4 ≈ 0.21586. Equal nonzero sRGB channels retain the model's D65 white-point chromaticity.
Interpreting the results
Chromaticity coordinates describe color independently of the luminance value. Keep the selected luminance units with your results. The browser preview may be normalized or clipped; use the numerical coordinates and calibrated instrument measurements for display acceptance decisions. Rounded input values can produce small differences when converting back.
Color-space references: ICC sRGB color encoding registry and W3C color-conversion reference examples.
Compare OLED targets with NVIS color limits
Plot up to ten named color points, draw tolerance regions, and compare their physically realizable overlap with MIL-STD-3009 NVIS Green A and Green B. Maximum-clearance points and inscribed circles help explore chromaticity margins; they do not establish spectral compatibility or compliance of an actual display.
Watch: OLED target and NVIS Green B overlap · Read MIL-STD-3009 Table II chromaticity limits · Search MIL-L-85762A lighting and daylight contrast requirements
Use color coordinates in your requirements
Record the input color space, white point, coordinate system, and whether luminance is relative or measured. Bring the source measurements, instrument details, and required tolerances when discussing display color evaluation or technical documentation.