Color tools

RGB to CMYK converter

Type the three RGB numbers from your design app — 46 204 113, rgb(46, 204, 113) or any CSS color — and get the conversion from RGB to CMYK as you type. It runs in your browser; nothing is sent anywhere.

CMYK

These are formula values, not an ICC conversion. For print, convert with your printer's profile or ask for a press proof — why.

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Contrast (WCAG)

Text on white
Text on black

How RGB becomes CMYK: the conversion formula

RGB describes light: three channels from 0 (off) to 255 (full). CMYK describes ink: how much cyan, magenta, yellow and black goes on paper, 0–100%.

  1. Divide each RGB number by 255, so it runs 0–1 (R′, G′, B′).
  2. K = 1 − the largest of the three. The brightest channel decides the black.
  3. C = (1 − R′ − K) ÷ (1 − K); M the same with G′, Y with B′.
  4. × 100 for percent. When K is 1 (pure black), C, M and Y are 0.

Worked example, rgb(46, 204, 113): R′ = 46 / 255 = 0.180, G′ = 0.800, B′ = 0.443. The largest is 0.800, so K = 0.200. C = (1 − 0.180 − 0.2) / 0.8 = 0.775; M = 0; Y = (1 − 0.443 − 0.2) / 0.8 = 0.446. That's cmyk(77.5%, 0%, 44.6%, 20%).

The walkthrough follows the color in the converter.

rgb(46, 204, 113)

RGB to CMYK values for common colors

Click a row to load it into the converter.

Color RGB CMYK
Black 0, 0, 0 0%, 0%, 0%, 100%
White 255, 255, 255 0%, 0%, 0%, 0%
Red 255, 0, 0 0%, 100%, 100%, 0%
Green (screen) 0, 255, 0 100%, 0%, 100%, 0%
Blue 0, 0, 255 100%, 100%, 0%, 0%
Cyan 0, 255, 255 100%, 0%, 0%, 0%
Magenta 255, 0, 255 0%, 100%, 0%, 0%
Yellow 255, 255, 0 0%, 0%, 100%, 0%
Mid gray 128, 128, 128 0%, 0%, 0%, 49.8%
Dark gray 64, 64, 64 0%, 0%, 0%, 74.9%
Orange 255, 165, 0 0%, 35.3%, 100%, 0%
Brown 165, 42, 42 0%, 74.5%, 74.5%, 35.3%
Pink 255, 192, 203 0%, 24.7%, 20.4%, 0%
Purple 128, 0, 128 0%, 100%, 0%, 49.8%
Teal 0, 128, 128 100%, 0%, 0%, 49.8%
Navy 0, 0, 128 100%, 100%, 0%, 49.8%

Pure screen green and blue get tidy numbers here, but no press prints them as bright as a monitor shows them.

Why a screen color looks duller in print

Light versus ink. RGB is the model for anything that emits light — screens, cameras, projectors. A screen adds red, green and blue light to black, and more means brighter. Print starts from white paper and takes light away with ink.

Gamut. Ink on paper can make fewer colors than a screen, and the gap is widest in vivid greens, blues and oranges. A formula always returns four numbers; it can't tell you a color is out of reach. A printer's ICC profile models the real ink and paper, moves such colors to the nearest printable one, and gives different numbers from these.

Rich black. The formula turns rgb(0, 0, 0) into K 100% alone. On a large area that prints as a dark gray, so printers often ask for a "rich black" with some cyan, magenta and yellow under the black. Small text stays K-only. Ask your printer for their recipe.

Converting a whole file, not one color

This converter turns one color value into CMYK numbers — for a brand spec, a print form or a palette. A photo, a PDF or a layout needs a color-managed conversion with the printer's profile:

If your printer accepts RGB files and converts them on their side, send RGB and ask for a proof.

RGB to CMYK: questions

Do I need to convert RGB to CMYK before printing?

Ask your printer. Many accept RGB files and convert them with their own profile; others want CMYK. Either way, one conversion with the right profile beats a chain of conversions, and a proof shows what you'll actually get.

Is RGB or CMYK better for printing?

CMYK is what a press prints, so the final file ends up in CMYK. Designing in RGB and converting once at the end, with the printer's profile, keeps more options open; designing in CMYK shows the limits up front. For brand colors, write down both values.

Can I convert RGB to CMYK without losing color?

Not always. Colors inside the printable range convert closely; vivid ones outside it get pulled in, whatever tool you use. The formula here can't flag them, so check bright greens, blues and oranges on a proof.

Why is black 0, 0, 0, 100 and not a rich black?

That's what the formula gives: it treats K as the only source of darkness. Large areas of K-only black print as a dark gray, so for those use your printer's rich-black recipe (some cyan, magenta and yellow under the black). Keep small text K-only.

Why does Photoshop give different CMYK numbers?

Photoshop converts through an ICC profile that models real inks, paper and ink limits. This page uses the plain formula, the same one most online converters and the Color API use: consistent and repeatable, but not tuned to any press.

Chrome extension

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Color API

Do it in code

curl "https://color.koval.tools/v1/convert?value=%232ECC71"

One call returns HEX, RGB, HSL, HSV, CMYK, Lab, LCH and OKLCH, with CMYK from the same formula. No key needed to try it. Convert docs · Pricing

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