# QR codes in CMYK print

> Print QR modules as 100% K: single-plate black. Rich black and converted RGB black are four-colour builds, and normal press misregistration of around 0.1 mm puts a coloured fringe on every module edge, blurring the whole grid at once, which error correction cannot repair.

Source: https://useqr.app/docs/print/qr-code-in-cmyk-print · Last reviewed 2026-08-21 · UseQR is free forever, no signup.

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## One plate or four

Offset CMYK builds every colour from four plates, and the plates never align perfectly:
a well-run press holds registration to around **±0.1 mm**. For photographs that drift is
invisible. For a QR code it is structural: a module on coated stock is only about
**0.4 mm**, so a 0.1 mm offset between plates smears a fringe across a quarter of every
module edge.

That is the entire argument for the rule: **QR modules print as 100% K, nothing else.**
One plate, no registration to hold, edges as crisp as the press can make them.

## The black builds compared

| Build | Plates | Result on a QR code |
|---|---|---|
| **100% K** | 1 | crisp edges, the correct choice |
| Rich black (e.g. C60 M40 Y40 K100) | 4 | fringing risk on every edge |
| RGB #000000, auto-converted | 4 | same risk, arrives by accident |
| Registration black (100/100/100/100) | 4 | never use, ink limit violations on top |

Rich black exists to make large solid panels look deeper, and it does. A QR code gains
nothing from that depth: the decoder thresholds luminance, and 100% K is already
comfortably past the [40% contrast requirement](/docs/design/qr-code-colors-that-scan) on
white stock, while paying the full registration and
[dot gain](/docs/print/ink-spread-and-dot-gain-in-qr-codes) price.

## The RGB paste accident

The most common route to a four-colour code is silent: an RGB PNG dropped into a CMYK
document. On export, colour management converts RGB black into a rich-black build across
all four plates, no dialog, no warning. The layout looks identical on screen, and the
problem only exists on press.

Two checks catch it every time:

1. **Separations preview** (Acrobat or InDesign output preview): turn off the K plate. A
   correct code *vanishes*; a converted one leaves a ghost image in C, M and Y.
2. **A loupe on the wet proof**: cyan or magenta shadowing along module edges means the
   build is wrong. That is precisely the failure to spot before signing the proof.

Placing a vector code and colouring it 100% K in the layout removes the risk entirely,
which pairs naturally with
[printing from SVG](/docs/print/why-you-should-print-qr-codes-from-svg).

## Background and error correction

Leave the background as unprinted paper (0% ink), and keep the
[quiet zone](/glossary/quiet-zone) ink-free. A light tint background is survivable if the
luminance difference stays above 40%, but it buys nothing.

Note what [error correction](/docs/spec/error-correction-levels-explained) can and cannot
do here: it repairs *localised* damage, and registration fringing degrades **every module
simultaneously**, so no EC level compensates. EC M is the sensible default; fix the ink
build, not the redundancy. If brand colour is essential, a single dark
[spot ink](/docs/print/spot-color-and-pantone-qr-codes) preserves the one-plate property.

Before the run: [validate the artwork](/validate), check the size against distance with
the [size calculator](/size-calculator), and walk the
[pre-press checklist](/docs/print/qr-code-print-checklist).

## FAQ

### Should a QR code be rich black or 100K?
100% K, always. Rich black prints from four plates, and normal registration tolerance of about 0.1 mm fringes every module edge, a quarter of a 0.4 mm module. Single-plate black has no registration to lose.

### Why does my printed QR code have coloured edges?
The black is a four-colour build (usually an RGB image auto-converted on export), and the plates are fractionally out of register. Rebuild the code as 100% K, or place a vector code coloured in the layout.

### How do I check a QR code is 100K before printing?
Open the print PDF in separations preview and hide the K plate: the code should disappear completely. Any residue on the cyan, magenta or yellow plates means the build is wrong.

### Can error correction fix registration blur?
No. Error correction repairs localised damage: a scuff, a stain, a logo. Misregistration degrades every module edge at once, which is a systemic loss the decoder cannot vote its way out of.

## Try it

- https://useqr.app/url
- https://useqr.app/validate
- https://useqr.app/size-calculator