CMYK to RGB Converter

By Suraj GiriUpdated 16 September 2026

A colour worked out from CMYK by formula is an estimate, not how the inks will print: with no ICC profile the conversion knows nothing about the inks, dot gain or the RGB space, and CSS Color 5 warns such an estimate can be visually very far from the printed result. A CMYK value sent to RGB and back can also return different inks, because the formula chooses black itself.

Going the other way? Convert RGB channels to CMYK inks →

How do I convert CMYK to RGB?

CMYK inks become RGB channels by formula: cmyk(20%, 40%, 0%, 10%) is rgb(184, 138, 230). Each channel starts at 255 and is scaled down twice, once by its own ink and once by black, then rounded to a whole number.

1. Type the four inks into the box. cmyk(20%, 40%, 0%, 10%), 20 40 0 10 and device-cmyk(0.2 0.4 0 0.1) all read.
2. Write each ink as a fraction from 0 to 1: 20% is 0.2 and 10% is 0.1.
3. For red, multiply 255 by (1 − C) and by (1 − K): 255 × 0.8 × 0.9 = 183.6. Green uses M and blue uses Y the same way.
4. Round each channel to a whole number, a value exactly halfway rounding up, so 229.5 becomes 230.
5. Copy the result, or swap the direction to turn the channels back into inks.

Different ink mixes can come out as the same RGB value; the CMYK vs RGB guide explains why a CMYK number describes a printer rather than a colour.

Black Ink Added to an Orange

Black scales every channel by the same factor. Half magenta and full yellow make an orange, and each step of K below takes red and green down by a fifth of where they started, before rounding, until at 100% black nothing is left.

Worked Example: cmyk(20%, 40%, 0%, 10%) to RGB

cmyk(20%, 40%, 0%, 10%) uses three inks, and its blue channel lands exactly halfway between two whole numbers, so the rounding rule shows. The working gives each channel before rounding and paints the result.

Rounded, the three channels give rgb(184, 138, 230). Sent back through the inverse formula it returns cmyk(20%, 40%, 0%, 10%), the inks this example started from. That is not guaranteed, because the formula chooses black itself and rounds every channel.

Check it in reverse

To check the result, work the channel values back into inks; expect the numbers to come back close, not always identical.

Worked examples: CMYK to RGB

Each example gives the value first, then the working. Select a value to load it in the converter.

Every example above converts back through the inverse formula — put the same channels back through the CMYK formula — but the inks that return can differ, because the formula chooses K itself.

What the Inks Give Back

Below are the rules this page follows, in the wording the site uses everywhere. The reference rows are what the converter reads: four inks, each from none to full.

What Does the RGB Result Not Know?

Ink, Paper and Dot Gain

Real ink on real paper does not behave like the formula. CSS Color 5 names what the formula has no knowledge of, including the colour of the inks and dot gain, and a conversion through an ICC profile for that press is what accounts for them.

Halfway Values Round Up

A channel that lands exactly halfway, such as 229.5, rounds up to 230. CSS Color 4 gives that rule for an rgb() value that cannot keep its fraction, and working the product exactly is what lets a true halfway value show.

Fractions Inside device-cmyk()

CSS Color 5 lets device-cmyk() take each ink as a fraction or a percentage, where 0 = 0%, 1 = 100%. Everywhere else this page reads a plain number as a percentage, and it refuses 0 0.5 1 0 rather than guess which was meant.

Common Mistakes

• Typing inks as fractions outside device-cmyk(). There a plain number is a percentage, so 0.5 would be half of one percent; the page refuses it and shows both spellings.
• Going above 100%. An ink runs from none to full, and 120% is refused rather than cut down to 100%.
• Expecting the screen colour to match the print. The RGB result is the formula's estimate, and the printed colour depends on the press.
• Leaving out the black ink. A CMYK value is four numbers, and three are refused with the count named.

Frequently Asked Questions

Related Conversions

• If you need a hex code rather than rgb(), write the same inks as a hex code instead.
• To take the result one step further, turn the RGB result into a hex code.
• If you hold a hex code rather than inks, read a hex code as channel values.
• The other way round, from a hex code — find CMYK inks for a hex code.

The rest of the family sits on the full set of colour converters.