Colortone to CMYK

Colortone to CMYK Converter

Look up the ink percentages behind any CSS color name. Enter Teal and get cmyk(100%, 0%, 0%, 49.8%); enter Sienna and get cmyk(0%, 48.8%, 71.9%, 37.3%). Names autocomplete as you type, and the result table also lists HEX, RGB, HSL, and HSV.

From a named screen color to a print spec

Web projects often start with CSS keywords – a prototype using Coral for buttons, or a brand sketch in ForestGreen. When the same color moves to business cards, flyers, or packaging, the printer needs CMYK. This tool uses the standard conversion:

• K = 1 − max(R, G, B) / 255
• C = (1 − R/255 − K) / (1 − K), and the same for M with green and Y with blue

Worked example: ForestGreen

ForestGreen is rgb(34, 139, 34). The largest channel is 139, so K = 1 − 139/255 = 45.5%. Cyan = (1 − 34/255 − 0.455) / 0.545 = 75.5%, magenta = 0%, yellow = 75.5%. The result is cmyk(75.5%, 0%, 75.5%, 45.5%).

Gamut shifts and ΔE

These numbers are a mathematical translation, not a promise of what the press will deliver. Vivid names such as Lime, Chartreuse, or DodgerBlue sit outside what CMYK inks can print, so the proof comes back noticeably duller. Print professionals quantify that shift with ΔE, most often the CIEDE2000 formula – the same perceptual metric FowTools uses to rank closest color names. A ΔE under about 2 between screen target and proof is usually signed off; a vivid green may miss by far more. For brand-critical colors, ask for a hard proof, or pick a calmer named color that prints reliably – you can check which names sit near an ink build with CMYK to Colortone.

For the full RGB breakdown of a name, see Colortone to RGB.