RGB to CMYK converter
Been told your cover or a picture in your book is RGB and needs to be CMYK? Put the image in here. You'll see whether your printer actually needs it, how the colours will shift in print, and get a CMYK file at exactly the same size and resolution, ready for your layout.
It's done in your browser. Your image isn't uploaded to Bervet and nothing is kept. The preview is open to everyone; saving the file is free for members.
1. Your image
No file to hand? (the ebook cover from The Signal by R. S. Breed).
CMYK: Recommended for print covers
KDP's cover guide says images "should be in CMYK color to ensure your cover looks good in print". It doesn't say an RGB cover is rejected. It asks for no colour profiles in the file and no mixing of colour types.
CMYK: Asked for
IngramSpark's file guide says cover images must be CMYK, and images in colour interiors too, with total ink no more than 240%. It converts RGB files to CMYK before printing, which can shift colours, and its upload check flags "Color space used". Black-and-white interiors should be greyscale.
CMYK: Not needed: RGB preferred
Lulu's printers work in both sRGB and CMYK and prefer sRGB, so you don't need to convert. Black-and-white interiors should be greyscale.
CMYK: Recommended
Bookvault asks for a CMYK workflow where possible.
CMYK: No published rule
Barnes & Noble Press doesn't publish an RGB or CMYK rule.
CMYK: No published rule for covers
Draft2Digital Print doesn't publish a colour rule for covers. Interiors print in greyscale only, and D2D converts them for you.
CMYK: Don't convert: use RGB
Ebook covers are for screens. Kindle needs RGB, and an RGB JPEG meets every store's rules. Only convert files that are going to be printed.
TIFF: for placing in InDesign, Affinity, Scribus or Word. PDF: one page at the image's printed size, if your printer wants a PDF.
Does your printer need CMYK?
From each platform's own pages, checked 4 October 2026.
| Platform | CMYK | What they say |
|---|---|---|
| Amazon KDP | Recommended for print covers | KDP's cover guide says images "should be in CMYK color to ensure your cover looks good in print". It doesn't say an RGB cover is rejected. It asks for no colour profiles in the file and no mixing of colour types. |
| IngramSpark | Asked for | IngramSpark's file guide says cover images must be CMYK, and images in colour interiors too, with total ink no more than 240%. It converts RGB files to CMYK before printing, which can shift colours, and its upload check flags "Color space used". Black-and-white interiors should be greyscale. |
| Lulu | Not needed: RGB preferred | Lulu's printers work in both sRGB and CMYK and prefer sRGB, so you don't need to convert. Black-and-white interiors should be greyscale. |
| Bookvault | Recommended | Bookvault asks for a CMYK workflow where possible. |
| Barnes & Noble Press | No published rule | Barnes & Noble Press doesn't publish an RGB or CMYK rule. |
| Draft2Digital Print | No published rule for covers | Draft2Digital Print doesn't publish a colour rule for covers. Interiors print in greyscale only, and D2D converts them for you. |
| Ebook covers (any store) | Don't convert: use RGB | Ebook covers are for screens. Kindle needs RGB, and an RGB JPEG meets every store's rules. Only convert files that are going to be printed. |
What the converter does
- Converts with a colour profile, the way design software does: GRACoL 2013, the current US standard for printing on coated paper.
- Keeps total ink to 240% (IngramSpark's limit) by lightening the coloured inks in the very darkest areas.
- Keeps every pixel: same width, height and resolution, so it places at the same printed size.
- Lays any see-through areas on white, because printers ask for no transparency.
- Leaves the colour profile out of the file, as KDP recommends (it removes them anyway).
Why the colours change
A screen makes colour with light; ink on paper can only reflect it. Some bright screen colours, especially vivid blues, greens, purples and pinks, can't be made with four inks, so they come out duller in print whoever converts them. The preview shows roughly how far, and can highlight the areas that change most. A CMYK file looks duller on screen: that's a fairer picture of the printed book, so don't brighten it back up. Order a proof copy and judge the real thing.
A whole cover?
If it's your full paperback or hardcover cover (back, spine and front) and the printer wants a PDF, use cover image to print PDF instead: it checks the size against your page count and makes the PDF at exactly the cover size, CMYK included.
Other profiles
Print-on-demand platforms don't publish the colour profiles their presses use, so the converter uses one standard, widely used profile for coated paper. Profiles for other presses, like the European FOGRA ones, aren't offered here. If your printer gives you its own profile, a design program can convert with it.
More on colour: RGB, CMYK and spot colours: fixing colour errors · Too much ink
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