CMYK is the colour mode required for all professional print production. If your PDF uses RGB, it must be converted to CMYK — and the quality of that conversion matters.
What CMYK Conversion Does
Converting a PDF to CMYK replaces all RGB colour values with their CMYK equivalents. Because the CMYK colour space is smaller than RGB, some colours will shift. A good conversion uses an ICC colour profile to manage this shift in a controlled way, producing the closest printable result.
Choosing the Right ICC Profile
The ICC profile determines how RGB colours are mapped to CMYK. Common choices:
- ISO Coated v2 (ECI) — standard for European coated paper (magazines, brochures, flyers)
- ISO Uncoated — for uncoated paper (letterheads, some brochures)
- FOGRA39 — widely used in European offset printing
- SWOP — standard for US print production
Ask your print shop which profile they require if you are unsure.
How to Convert in Design Software
In Photoshop: Edit → Convert to Profile → select the target CMYK profile. In Illustrator: Edit → Assign Profile or use the colour mode setting. In InDesign: set the export colour space to CMYK in the PDF export dialog.
Automatic PDF to CMYK Conversion
If you only have a PDF (no source file), use PrintConvert247 to convert it to CMYK automatically using a professional ICC profile.
Convert your PDF to CMYK — automatically
Upload your file and get a CMYK-compliant print-ready PDF in seconds.
Convert to CMYK →Verify After Conversion
After converting, check the result with PrintReady247 to confirm the file is fully in CMYK and has no remaining RGB elements.