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Convert RGB to CMYK

Format

RGB

Red (R)R

Green (G)G

Blue (B)B

Reset

CMYK

0, 20, 98, 6

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CMYK values are approximate. For production printing, use ICC profile-based conversion in your design software.

How to convert RGB to CMYK

Normalize each RGB value to the 0–1 range by dividing by 255. Compute the Key (black) channel: K = 1 − max(R, G, B). If K = 1, the color is pure black and C=M=Y=0. Otherwise, C = (1−R−K)/(1−K), M = (1−G−K)/(1−K), Y = (1−B−K)/(1−K). Multiply each result by 100 to express as a percentage.

When to use RGB vs CMYK

RGB is the standard for digital screens — every pixel on your monitor is a combination of red, green, and blue light. CMYK is the standard for commercial printing — inks are layered on paper in cyan, magenta, yellow, and black. You need this conversion when sending digital artwork to a print shop, or when adding a print-defined color to a design file that uses RGB.

Worked example

Convert RGB(0, 128, 255) to CMYK: Normalize: R=0, G=0.502, B=1.0. K = 1−1.0 = 0. C = (1−0−0)/(1−0) = 1.0 → 100%. M = (1−0.502−0)/(1−0) = 0.498 → 50%. Y = (1−1.0−0)/(1−0) = 0 → 0%. K = 0%. Result: CMYK(100, 50, 0, 0) — a vivid sky blue. The zero Key value means no black ink is used.

CMYK gamut limitations

CMYK cannot reproduce every RGB color. Highly saturated neon colors, electric blues, and bright greens may look duller in print. If color accuracy is critical, ask your print vendor for a Pantone spot color match instead of relying on the four-color CMYK process. The values from this tool are a mathematical approximation and should be verified with a physical proof before a production run.

Frequently asked questions

How do I convert RGB to CMYK?
First, normalize RGB values to 0–1 by dividing by 255. The Key (black) channel is K = 1 - max(R, G, B). Then C = (1 - R - K) / (1 - K), M = (1 - G - K) / (1 - K), Y = (1 - B - K) / (1 - K).

Why do my CMYK colors look different when printed?
RGB-to-CMYK conversion is a mathematical approximation. True color matching for print requires ICC profiles specific to your printer, ink, and paper. This tool gives you a starting point; consult your print vendor for production-grade accuracy.

What is the difference between RGB and CMYK?
RGB is additive (light-based, for screens) and CMYK is subtractive (ink-based, for print). RGB can produce brighter and more saturated colors than CMYK. Neon and fluorescent colors visible on screen cannot be accurately reproduced in CMYK.

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