Screen colors and printed colors differ. Verify CMYK values early — before InDesign, Illustrator, or your US/UK print shop flags a gamut issue.

Every design that starts on screen — Figma mockups, Photoshop comps, Illustrator logos — uses RGB. The moment that design goes to a US or UK commercial printer, magazine publisher, or packaging manufacturer, the file must be in CMYK. RGB and CMYK use fundamentally different physics: RGB adds light, CMYK subtracts ink from white paper. A bright Figma blue like rgb(59, 130, 246) may print noticeably duller without prior gamut checking.
Adobe InDesign and Illustrator let you define swatch colors in CMYK directly, but you still need the values to enter. Brand guidelines often provide RGB and Pantone references — this converter lets you derive the CMYK equivalent for spot-to-process matching or magazine ad submissions that specify CMYK-only files.
Book covers, retail packaging, and business card print runs in the UK and US typically require files with total ink coverage (TIC) under 300%. Checking your CMYK values here before opening InDesign saves costly reprints.
All calculations run locally in your browser — nothing is sent to any server.
First, normalize RGB to 0–1 range: R'=R/255, G'=G/255, B'=B/255. K = 1 − max(R', G', B'). C = (1−R'−K)/(1−K). M = (1−G'−K)/(1−K). Y = (1−B'−K)/(1−K).
This is a mathematical conversion. Actual printed results depend on ink, paper, and ICC profiles. For production printing, use ICC profile-based conversion in Photoshop or InDesign.
This converter provides a mathematical estimate. For critical color work, always use proper ICC profiles and get a proof print.
| Feature | RGB | CMYK |
|---|---|---|
| Model | Additive (light) | Subtractive (ink) |
| Used for | Screens, web | Print, packaging |
| Gamut | Wider (more colors) | Narrower |
| Black | R=0, G=0, B=0 | K=100% |
| White | R=255, G=255, B=255 | No ink (paper) |
Screens emit light using RGB (additive model) — mixing R+G+B=white. Printers deposit ink on paper using CMYK (subtractive model) — mixing C+M+Y+K=black. The CMYK gamut is roughly 50–70% of the RGB gamut, so vivid screen colors like Figma's electric blue or neon green simply cannot be reproduced with ink. Converting early lets you adjust expectations before the press run.
Pure black in CMYK is K=100%, but this often looks slightly grey on large print areas. Rich black (typically C=60%, M=40%, Y=40%, K=100%) produces a deeper, denser black. Use rich black for headlines, large background areas, and covers. For small body text, use pure K=100% to avoid registration issues.
TIC is the sum of C+M+Y+K percentages. Most commercial printers in the US and UK set a maximum of 300–320%. Exceeding it causes ink smearing, longer drying times, and paper damage. Check your CMYK values and sum the four channels before submitting print-ready files.
Design in RGB if your deliverable is primarily digital (web, app, social). Design in CMYK if print is the primary output. For dual-use projects — a brand identity that spans website and printed brochure — design in RGB and convert to CMYK for print delivery, using ICC profiles in Photoshop or InDesign for accurate conversion.
This converter uses a mathematical formula (no ICC profile). It is ideal for quick checks, developer workflows, and ballpark values. Adobe Photoshop and InDesign use ICC color profiles (e.g., US Web Coated SWOP v2 or Fogra39) which account for specific ink and paper combinations. For production print work, always use ICC profile-based conversion and request a proof print.
Yes, as a starting reference. Open the Swatches panel in InDesign, create a CMYK swatch, and enter the C, M, Y, K percentages shown here. For critical color work — packaging, magazine covers, Pantone-matched brand colors — follow up with an ICC profile conversion and a physical proof.
No. All RGB to CMYK calculations run entirely in your browser. Nothing is transmitted anywhere. The tool works offline once the page has loaded.

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