RGB or CMYK for print: what to do in an RGB-only tool
Printers press in CMYK; most design tools, including this one, work in RGB. What the difference is, why sending RGB is usually right, what to say to the printer, and the three things to change in the design so the conversion goes well.
Beginner4 min readUpdated 27 September 2026Editor · Print PDF
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What the two are
| RGB | CMYK | |
|---|---|---|
| Made of | Red, green and blue light, added together | Cyan, magenta, yellow and black ink, layered on paper |
| Used by | Screens, cameras, the web, most design tools | Presses and most professional printers |
| Range of colours | Wider, especially bright and saturated colours | Narrower; bright blues, greens, oranges and pinks are out of reach |
| White | All three at full | The paper; no ink |
| Black | All three at zero | Black ink alone (pure black) or black plus colour (rich black) |
| In a file | Three numbers per pixel, or a hex code | Four percentages per colour, plus a profile that describes the press |
There is no single CMYK. A conversion depends on a profile (the press, the ink set and the paper), so "convert to CMYK" without a profile is a guess. That is why the printer, who knows the profile, is the better place for it.
What to change in the design
- Do not build on a neon. Bright saturated colours shift most. Use them small; use a slightly deeper version of the colour for large surfaces.
- Text in pure black. RGB black (#000000) converts to a mix of all four inks in a generic conversion, which looks fuzzy on small type if the plates are a fraction out. Ask the printer to keep text as 100 per cent K; most do this by default for black text.
- Large black areas as rich black. Black ink alone prints as a dark grey on big areas. Printers add cyan and magenta to deepen it. Say "rich black for large areas" in the note and let them set the mix.
- Check light tints. Very pale colours (a 3 per cent tint) can disappear or come out patchy. Keep tints above about 8 per cent.
- Look at a printed sample of the brand colour before a big run. A proof answers what no preview can.
When the printer says CMYK only
Some printers, especially trade printers with automated preflight, reject RGB files. Three ways through, in order of preference:
- Ask. "I can supply RGB; can you convert with your profile?" Most will, and a note in the order form is usually enough.
- Have them convert as a paid prepress step. Small fee, correct profile.
- Convert it yourself in a tool that exports CMYK PDFs (a desktop layout or vector app), choosing the profile the printer names, usually a coated or uncoated FOGRA or SWOP profile. Open the exported RGB PDF or PNG there, place it on a page of the right size, and export as PDF/X. Expect the on-screen colours to look duller after conversion; that is the preview being honest.
How Voidcanvas handles this
Every export is RGB. Studio's print PDFs say so in the slug line, with bleed and crop marks; the Editor's PDF does not label itself, so put RGB in the order note. Both are image-based at 300 dpi, which printers accept and convert with their own profile. There is no CMYK export, no soft proof and no profile embedding. The brand guideline builder keeps colours in OKLCH ramps, which makes it easy to pick a less saturated step for print surfaces, and the print-setup preview above shows which colours are going to move.
Can I print an RGB file?
Yes. Home printers expect RGB, and most commercial and online printers accept RGB PDFs and convert them with their press profile. Say RGB in the order note so nobody assumes.
Why does CMYK look dull on screen?
The screen is showing you a simulation of what ink can do. Ink reflects light; a screen emits it. The dullness is the truth about paper, not a fault in the file.
Should I design in CMYK from the start?
Only if the tool and the printer both support a specific profile and you have a calibrated screen. Otherwise design in RGB, avoid out-of-gamut colours, and proof.