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RGB to CMYK Converter

Convert RGB screen colors to CMYK print percentages (and back) instantly, right in your browser.

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

How to use

  1. 1.Enter your color as RGB (each channel 0–255) to see the equivalent CMYK percentages, or enter CMYK percentages (0–100) to get RGB back.
  2. 2.Read the CMYK, RGB and HEX values and check the live color swatch preview to confirm you have the right color.
  3. 3.Click Copy next to any format to grab the value for your design or print file.

About RGB to CMYK Converter

RGB to CMYK is the bridge between how a color looks on screen and how it prints on paper. RGB is an additive model: red, green and blue light add together, and full intensity of all three gives white — it's how monitors, phones and cameras make color. CMYK is subtractive: cyan, magenta, yellow and a black key (K) are inks that absorb light, and layering all of them on white paper moves toward black. That inversion is why bright, glowing screen colors often look flatter once printed — the two models simply cover different color spaces.

This tool converts both directions. Type an RGB value (0–255 per channel) and it returns CMYK as four percentages; type CMYK percentages (0–100) and it returns the matching RGB. The math is the standard naive formula: each RGB channel is scaled to 0–1, K is set to 1 minus the largest of the three channels, and C, M and Y are what's left over after removing that black component. Pure black is handled as a special case (K = 100%, no colored ink), and out-of-range inputs are clamped so you never get a broken result.

The K channel exists for a practical reason: printing a rich black from cyan, magenta and yellow alone wastes ink, over-saturates the paper and rarely looks truly black. A dedicated black plate is cheaper, sharper, dries faster and is used for all text, so K is broken out as its own channel instead of being mixed from the other three.

Typical uses are everyday design-to-print tasks: converting a brand color from a website palette into CMYK before sending a flyer, business card, poster or packaging file to a printer; sanity-checking that a logo color won't shift wildly on paper; or simply learning why the same hex code looks different on screen and in print. Because it also converts CMYK back to RGB, you can take a value from a print spec and preview roughly how it will appear on a display.

A few things worth knowing about the numbers. The conversion treats RGB as plain sRGB-style values without a source or destination profile, so it has no idea which press or paper you'll use. It also can't invent colors that ink can't make: neon greens, electric blues and bright oranges live outside the CMYK gamut and will be approximated, which is the real reason vivid screen colors can look muted in print.

One honest caveat, stated plainly: this is a plain mathematical conversion, not ICC color management. Real print shops convert through a specific CMYK profile (US Web Coated SWOP, FOGRA39, Japan Color and others) that accounts for the actual inks, paper and dot gain of the press. Those numbers will differ from the naive result here — sometimes noticeably. Use this converter for quick estimates, for understanding how the two models relate, and for getting a sensible starting CMYK value — then trust your printer's profile and a proof for the final production file.

Everything runs locally in your browser. No color is uploaded, so it stays fast, private and works offline once the page has loaded.

Methodology & sources

Naive RGB↔CMYK conversion. From RGB: R',G',B' = channel/255; K = 1 − max(R',G',B'); if K=1 then C=M=Y=0 else C=(1−R'−K)/(1−K), M=(1−G'−K)/(1−K), Y=(1−B'−K)/(1−K); C/M/Y/K output as percentages (0–100). Inverse from CMYK: R=255·(1−C/100)·(1−K/100), G=255·(1−M/100)·(1−K/100), B=255·(1−Y/100)·(1−K/100). Note: this is plain math, not ICC color management, and is approximate versus real print output.

Frequently asked questions

How accurate is this RGB to CMYK conversion?
It uses the standard naive math formula, which is great for quick estimates and understanding how the models relate. It is not ICC color-managed, so a professional print shop converting through a real CMYK profile (like SWOP or FOGRA39) will get slightly different percentages that account for actual inks, paper and press behavior.
Why can't RGB colors always be printed exactly in CMYK?
RGB is additive (light) and covers a wider, brighter gamut than CMYK, which is subtractive (ink on paper). Very bright or highly saturated screen colors fall outside what CMYK inks can reproduce, so they get approximated and can look duller in print. That gamut gap, not a conversion bug, is why the printed result may differ from your monitor.
What is the K channel in CMYK?
K is the black key plate. In theory cyan, magenta and yellow together make black, but in practice that muddy mix wastes ink and never looks truly black. A separate black plate produces cleaner blacks, crisp text and lower ink cost, which is why K is its own channel.

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