RGB vs CMYK: Why It Matters More Than You Think*

Two Different Worlds

RGB (Red, Green, Blue) is the colour model used by screens — your monitor, phone, and TV all mix light to create colour. Add all three together and you get white. Remove them all and you get black. It's an additive system.

How RGB Works

Think of it like light. A phone screen emits red, green, and blue light in varying intensities. Your eye mixes these together and perceives the final colour. This is why screens can display impossibly bright, saturated colours — they're literally producing light.

CMYK (Cyan, Magenta, Yellow, Key/Black) is the model used in printing. Inks are layered on white paper, each absorbing certain wavelengths of light. Add them all together and you get a very dark brown (hence the need for dedicated black ink). It's a subtractive system.

How CMYK Works

With print, you're starting with white paper and subtracting light by laying down coloured inks. This is fundamentally different. You can't create light — you can only remove it. That's why printed colours look different from screen colours, no matter how hard you try.

Why This Causes Problems

The RGB colour gamut is significantly larger than CMYK. This means there are colours your screen can display that simply cannot be reproduced with ink on paper. Vivid electric blues, bright neons, and saturated greens are particularly prone to this — they look stunning on screen and flat, dull, or shifted in print.

The Gamut Gap

When a printer's RIP (Raster Image Processor) converts an RGB file to CMYK, it makes its best guess at matching colours. Sometimes the result is fine. Often it isn't — and you won't know until you see the printed sheet. This unpredictability is costly.

The problem gets worse the more vibrant your original colours. A pastel blue might convert fine. That electric neon blue? It'll look completely different.

Unexpected Shifts

The most common surprise is how dramatically certain colours shift. That electric blue becomes muddy. The vibrant green turns olive. The hot pink becomes mauve. These aren't small tweaks — they're complete transformations that can ruin brand identity or product presentation.

You'll only discover this when you see the actual printed piece, which is why so many designers get caught out.

One issue we regularly see in supplied artwork is a brand colour that's been designed in RGB and looks perfect on screen, only to fall flat in print. We always check for potential gamut issues during pre-press and flag them before the job goes to press — it's far cheaper to adjust before printing than after.

How to Get It Right

1. Work in CMYK from the start

For any project destined for print, set your document colour mode to CMYK in InDesign, Illustrator, or Photoshop before you begin. This forces you to design within the constraints of what can actually be printed.

Yes, your designs will look less vibrant while you're working. That's the point — you're seeing what the client will actually receive.

2. Use Pantone (PMS) references

Pantone spot colours can be matched precisely regardless of CMYK limitations. For brand-critical colours, always supply a Pantone reference alongside your CMYK values.

If your brand colour is a specific orange, get the Pantone number and specify it. Don't rely on CMYK values alone — they vary by printer.

3. Request a printed proof

Before committing to a full run, request a physical proof and view it under consistent lighting. This is the only reliable way to approve colour.

Don't approve a PDF proof. Don't approve a monitor display. Get something printed on the actual substrate you'll be using.

4. Don't trust your monitor

Even calibrated screens vary wildly. Your printer's proof is the benchmark, not your display.

This can't be overstated: your monitor is lying to you. Even expensive, professionally calibrated monitors. Printers' proofs don't lie.

The Bottom Line

Understanding RGB vs CMYK isn't just technical pedantry — it's the difference between getting what you expected and being disappointed by the result. If in doubt, talk to us before you start designing — our creative design team works in the right colour space from day one.