RGB to CMYK colour space converter — quick approximate print values

How to use the colour space converter

1. Click RGB colour and pick a colour, or type a HEX code such as #2563eb.
2. Read CMYK (approximate) at the top.
3. Copy the RGB, HEX or HSL form if you need the colour for screen work too. A swatch shows the screen colour.

What it does and when to use it

Screens make colour by mixing red, green and blue light (RGB). Printers lay down cyan, magenta, yellow and black ink (CMYK). When a logo or brand colour exists only as a HEX code, you need some CMYK numbers to give a designer or a print form. This tool gives a fast, consistent first estimate.

Use it to fill in a CMYK field on a print order, to check that a colour will need a lot of ink coverage, or to compare two brand colours. For a full conversion table across many formats, use the colour converter. To go from CMYK back to screen colours, use CMYK to RGB. To get a colour out of a photo first, try the image colour picker.

How it works

The tool uses the simple device-independent formula. With R, G and B scaled from 0–255 to 0–1:

• K = 1 − max(R, G, B)
• C = (1 − R − K) ÷ (1 − K)
• M = (1 − G − K) ÷ (1 − K)
• Y = (1 − B − K) ÷ (1 − K)

Each value is shown as a percentage to one decimal place. Pure black is a special case: K is 100% and the others are 0. HSL comes from the same RGB values: hue in degrees, saturation and lightness in percent. Nothing leaves your browser.

Worked examples

These results come from the tool’s own function.

• A strong blue, #2563eb (rgb 37, 99, 235). The largest channel is blue at 235, so K = 1 − 235/255 = 7.8%. The result is C 84.3% M 57.9% Y 0% K 7.8%, and HSL is hsl(221.2, 83.2%, 53.3%).
• A green, #22c55e (rgb 34, 197, 94). Green is the largest channel, so magenta is 0: C 82.7% M 0% Y 52.3% K 22.7%.
• Middle grey, #808080. All channels are 128, so only black ink is used: C 0% M 0% Y 0% K 49.8%.

Limits and tips

• No ICC profile is applied, and the paper type, ink limits and dot gain of a real press are ignored.
• The total ink can differ from what a press allows; printers often cap it.
• For brand colours that must match exactly in print, use a spot colour system agreed with your printer.