# Why your barcode must be 100% K, not rich black

> A black mixed from several inks prints a barcode on several plates, and any shift blurs the bars. Why KDP and IngramSpark ask for 100% K, and how to keep it.

- Author: Marko Markovic, prepress specialist (https://barcoderocket.com/about)
- Publisher: Barcode Rocket (https://barcoderocket.com/)
- URL: https://barcoderocket.com/articles/100-percent-black-barcode
- Published: 2026-10-10
- Updated: 2026-10-10
- Topic: Print quality: 100% K, vector, size
- Sources: 5, listed at the end

## Short answer

A barcode must be printed in one ink, 100% black (C0 M0 Y0 K100), because a black made of several inks prints from several plates, and even a tiny shift between plates widens and blurs the bars. IngramSpark asks for black only, 0/0/0/100, and KDP's help words it as "100% black (not RGB/CMYK color or registration black)". 100% K is itself a CMYK value; what both platforms rule out is a black mixed from several inks, or an RGB black that gets converted into one. On screen you cannot see the difference; in the separations of the PDF you can.

## Three kinds of "black"

| Name | CMYK values (example) | Plates it prints on | For a barcode |
|---|---|---|---|
| 100% K | 0 / 0 / 0 / 100 | Black only | Correct |
| Rich black | for example 60 / 40 / 40 / 100 | All four | Wrong |
| Registration | 100 / 100 / 100 / 100 | All four, and every spot plate | Wrong, and too much ink |
| RGB black | 0, 0, 0 in RGB | Depends on conversion, usually all four | Wrong |

Rich black is a perfectly good tool for large black backgrounds, where it gives a deeper black than ink alone. It is wrong for anything thin and precise: small text, hairlines and barcodes.

## What happens on press

A four-color press prints each ink from its own plate, one after another. The plates are aligned (in register), but never perfectly: paper stretches, it moves slightly between units, and every press has tolerance. On a photo, a shift of a fraction of a millimeter is invisible. On a barcode it is not:

![Rich black on four slightly shifted plates (left) and 100% K on one plate (right).](https://barcoderocket.com/articles/fig/rich-black.svg)

*Figure: Rich black on four slightly shifted plates (left) and 100% K on one plate (right).*

- **The bars get wider.** Four slightly offset bars cover more paper than one. A barcode encodes information in the exact widths of bars and spaces, so wider bars eat into the spaces.
- **The edges get colored fringes.** Cyan, magenta or yellow peek out at the edges. A scanner sees a soft edge instead of a clean one.
- **The ink piles up.** Four inks on top of each other can spread more on absorbent paper, which makes bars grow further.

With 100% K there is one plate, so there is nothing to fall out of register.

## Where the black gets lost

Most designers set the barcode in black. The problem is that "black" in a design program is not always 100% K:

- **RGB documents.** In an RGB document, black is RGB 0,0,0. Converted to CMYK on export, it usually becomes a four-color black.
- **Color conversion on export.** A PDF export that converts colors to a destination profile can turn 100% K into a mix, or into a gray below 100%. IngramSpark warns about ICC profiles turning 100% black text into a shade of gray.
- **Barcode from an image.** A PNG or JPG barcode is RGB or grayscale. Placed in a CMYK cover and converted, its black usually becomes a mix.
- **Default "rich black" swatches.** Some templates use a rich black swatch named "Black".

## How to keep it 100% K

1. Start with a barcode that is already 100% K vector. Every Barcode Rocket PDF is C0 M0 Y0 K100.
2. Place it, do not paste or recolor it.
3. Export your cover PDF with a setting that does not convert colors (for example, "No Color Conversion" or "Preserve Numbers" in the output settings), or with your printer's preset if it keeps the K channel.
4. Check the final PDF in Acrobat Pro, Output Preview, Separations: with only Black visible, the barcode must be complete. [Step by step](https://barcoderocket.com/articles/is-my-barcode-vector).

> Overprint: on covers where black overprints the background, a 100% K barcode on a white box is safe either way, because there is nothing under it. On a colored background without a white box, the barcode would mix with the color below, which is another reason for the white box.

[Make a 100% K barcode: open the free ISBN generator](https://barcoderocket.com/?type=isbn#try)

## Frequently asked questions

### Is a CMYK barcode OK?

Yes, if its CMYK values are C0 M0 Y0 K100. What is not OK is a black that also uses cyan, magenta or yellow (rich or registration black): it prints on several plates and can blur.

### Will my printer fix it?

Not reliably. Some print workflows convert small black text to 100% K, but you cannot count on it for a barcode, and KDP and IngramSpark check it.

### Does 100% K look gray?

On large areas, 100% K is slightly less deep than rich black. On thin bars on white, it looks black, and it is what every scanner expects.

### My barcode is RGB 0,0,0. Is that black enough?

On screen, yes. In print, it depends on the conversion, and it usually becomes a four-color black. Use a barcode set in C0 M0 Y0 K100.

## Sources

- Amazon KDP Help, Barcodes (100% black requirement): [kdp.amazon.com](https://kdp.amazon.com/en_US/help/topic/G5HDYGP4BXLX4RUW)
- IngramSpark, Understanding IngramSpark Title Processing (black only, 0/0/0/100): [ingramspark.com](https://www.ingramspark.com/blog/understanding-ingramspark-title-processing)
- IngramSpark Help, Cover File Creation (ICC profiles and 100% black): [help.ingramspark.com](https://help.ingramspark.com/hc/en-us/articles/35306346735245-Cover-File-Creation)
- Adobe Help, Previewing output (Acrobat Pro): [helpx.adobe.com](https://helpx.adobe.com/acrobat/current/previewing-output-acrobat-pro.html)
- GS1 General Specifications (bar and space widths): [ref.gs1.org/standards/genspecs](https://ref.gs1.org/standards/genspecs/)