What is the CMYK to RGB formula?

Each RGB channel equals 255 times (1 minus the ink) times (1 minus black). For example R = 255 * (1 - C/100) * (1 - K/100). This is the standard naive conversion used when no ICC colour profile is involved.

Will the screen colour exactly match my print?

Not always. CMYK is device and paper dependent and uses ICC profiles for accurate proofing. This tool gives the standard mathematical conversion, which is ideal for web mockups and quick previews.

What does the K in CMYK stand for?

K stands for Key, which is the black ink. It is called the key plate in printing because the other colours are aligned (keyed) to it. A higher K darkens every channel.

What RGB is CMYK 0, 100, 100, 0?

Pure red — rgb(255, 0, 0). With no cyan and no black, and full magenta and yellow, red is at maximum while green and blue drop to zero.

Is anything sent to a server?

No. The conversion runs entirely in your browser — nothing is uploaded or logged.

CMYK to RGB Converter

CMYK describes the four printing inks — cyan, magenta, yellow and key (black) — while RGB describes the red, green and blue light a screen emits. This converter turns CMYK ink percentages into the equivalent RGB value with a live colour swatch, so you can preview a print colour on screen or pull a print value into web and CSS work.

How it works

The tool applies the standard mathematical CMYK-to-RGB conversion (used when no ICC colour profile is involved). Each ink percentage is divided by 100, then each RGB channel is computed as 255 scaled down by the relevant ink and by black:

R = 255 × (1 − C) × (1 − K) G = 255 × (1 − M) × (1 − K) B = 255 × (1 − Y) × (1 − K)

Higher ink values subtract more light, and the black (K) channel dims all three at once. Results are rounded to whole 0-255 values and shown as a CSS rgb() string.

Example

Convert C 76, M 47, Y 0, K 4:

R = 255 × (1 − 0.76) × (1 − 0.04) ≈ 59 G = 255 × (1 − 0.47) × (1 − 0.04) ≈ 130 B = 255 × (1 − 0) × (1 − 0.04) ≈ 245

The result is rgb(59, 130, 245), a bright blue. Note that this is a mathematical conversion — exact print matching needs ICC profiles, since CMYK is device and paper dependent. Everything runs in your browser, nothing uploaded.