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CMYK To RGB

Preview uncalibrated CMYK percentages as an approximate screen RGB color and hex value.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Set cyan, magenta, yellow, and black to percentages from 0 through 100.
  2. 2.Read the approximate RGB channels, hexadecimal value, and screen swatch.
  3. 3.Use an ICC-profile-aware application instead when print accuracy matters.

About CMYK To RGB

CMYK to RGB converts four device-CMYK ink percentages into an approximate screen color. Adjust cyan, magenta, yellow, and black from zero to one hundred percent and the page immediately displays 8-bit red, green, and blue channels, a six-digit hexadecimal value, and a visual swatch. It is useful for quick interface mockups, rough palette comparisons, and checking how an uncalibrated CMYK recipe might look on an sRGB-style display.

The calculation follows the naive device-CMYK fallback published in the W3C CSS Color work. Each color ink is combined with black, inverted, scaled to the 0–255 display range, and serialized to an integer channel. Familiar endpoints behave predictably: no ink produces white, full black produces black, and full magenta plus yellow with no cyan or black produces red. The implementation includes independent fixtures for primary endpoints, mixed channels, and the W3C firebrick example.

This result is deliberately labeled an approximation. Real CMYK is device-dependent: the press, ink set, paper, dot gain, rendering intent, and embedded ICC profile can materially change the printed appearance. Professional applications use source and destination color profiles when converting between CMYK and RGB. This browser tool does not load an ICC profile and must not be used as a press proof, contractual color target, or substitute for a calibrated workflow.

For a quick preview, copy the four percentages from an unprofiled color recipe, move the sliders to those values, and use the displayed RGB or hex code in a screen mockup. For print production, keep the original CMYK values, ask the printer for the correct output profile, and use profile-aware software with a calibrated display and physical proof. The calculation stays in the browser and sends no color values to a server.

Methodology & sources

Percentages are normalized to 0–1, then each display channel uses 1 - min(1, colorInk × (1 - black) + black), scaled to 255 and serialized with half-even tie rounding to match the W3C firebrick example. No ICC profile is applied.

Frequently asked questions

Is this conversion accurate for printing?
No. It is an uncalibrated screen approximation. Print-accurate conversion requires the correct ICC profiles and proofing workflow.
Why can Photoshop or a printer show different RGB values?
Profile-aware software accounts for a specific CMYK and RGB color space, rendering intent, ink, and output device; this tool uses the W3C naive fallback.
Are my color values uploaded?
No. Conversion and preview happen locally in your browser.

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