CMYK vs RGB: Why It Matters for Print

Two Colour Systems, Two Very Different Results

Every colour you see on a screen is made from light. Every colour you see on a printed page is made from ink. These two systems work in completely different ways, and if you mix them up, your printed materials will not look the way you expected.

The screen system is called RGB. The print system is called CMYK. Understanding the difference takes about five minutes, and it will save you from disappointing results and wasted money.

What Is RGB?

RGB stands for Red, Green, Blue. These are the three colours of light that screens use to create every colour you see on your monitor, phone, or tablet. When all three are turned up to full intensity, you get white. When all three are off, you get black.

RGB can produce an enormous range of colours, roughly 16.7 million combinations. This includes extremely vivid neon greens, electric blues, and bright purples that practically glow on screen. Cameras capture in RGB, screens display in RGB, and most design software defaults to RGB.

What Is CMYK?

CMYK stands for Cyan, Magenta, Yellow, and Key (black). These are the four ink colours used in commercial printing. Instead of mixing light, CMYK works by layering semi-transparent inks onto paper. Each ink absorbs certain wavelengths of light and reflects others, which is how you see colour on the printed page.

Cyan ink absorbs red light. Magenta absorbs green. Yellow absorbs blue. In theory, mixing all three should produce black, but in practice it creates a dark muddy brown. That is why black ink (the "Key" colour) is added separately.

Why RGB Does Not Work for Print

The problem is simple: ink on paper cannot reproduce all the colours that light on a screen can. RGB has a wider "gamut" (range of possible colours) than CMYK. Those vivid neon greens and electric blues that look brilliant on your monitor simply cannot be recreated with four inks on paper.

When a printer receives an RGB file, the software has to convert those colours to the nearest CMYK equivalent. The results are often disappointing. Bright oranges go dull. Vivid purples shift towards blue. Neon greens become flat and lifeless. The overall image can look washed out compared to what you saw on screen.

This is not a fault with the printer or the paper. It is a physical limitation of how ink works. The good news is that you can manage this yourself by converting your files to CMYK before you send them, so you can see the colour shift on screen and make adjustments.

How to Convert to CMYK in Photoshop

Open your file and go to Image > Mode > CMYK Color. Photoshop will show you a warning that colours may shift. Click OK and then look at your image carefully. If certain colours have gone flat, you can adjust them using Curves or Hue/Saturation before saving.

Save your final file as a PDF or high-resolution TIFF. Make sure the colour profile is set to a standard CMYK profile such as Fogra39 (for coated paper) or Fogra47 (for uncoated paper). These profiles are industry standard across Europe.

How to Convert to CMYK in Illustrator

Go to File > Document Color Mode > CMYK Color. This changes the entire document. If you have already placed images, they will preview in CMYK. For the most accurate results, convert any linked images to CMYK in Photoshop first, then re-link them in Illustrator.

When exporting your final PDF, use the Press Quality preset or a custom preset with CMYK output. Avoid "Smallest File Size" presets as these are designed for screens, not print.

What About Canva?

Canva is popular with small business owners, and for good reason. It is quick and easy to use. However, CMYK export is only available on Canva Pro. If you have a Pro account, go to Share > Download, select PDF Print, and tick the CMYK checkbox and the Flatten PDF option.

If you are on the free version of Canva, your files will export in RGB. You can still send them to us and we will convert them, but be aware that some colours may shift. If colour accuracy is important for your brand, consider upgrading to Pro or using a different tool for your print work. For full details on preparing files, see our artwork guidelines.

Colours That Cause the Most Trouble

Some colours convert from RGB to CMYK without much visible change. Earth tones, muted blues, and warm reds tend to look similar in both modes. Other colours shift dramatically:

• Bright orange: Often goes duller and slightly brown
• Vivid purple: Shifts towards blue or looks less saturated
• Neon green: Loses almost all of its vibrancy
• Electric blue: Becomes darker and less punchy
• Hot pink: Can shift towards magenta or lose brightness

If your brand colours include any of these, it is worth doing a test print before ordering a large batch. You can also ask us for a printed colour proof.

A Note on Pantone and Spot Colours

For precise colour matching (brand logos, for example), some businesses use Pantone spot colours. These are pre-mixed inks that match a specific numbered swatch, so the colour is consistent every time. Spot colour printing costs more and is typically used for litho runs rather than digital printing. For most small business print jobs, CMYK will do the job well.

Practical Steps Before You Send Your Files

• Set your document to CMYK from the start, before you begin designing
• If you have already designed in RGB, convert and then check every colour carefully
• Use CMYK colour values when choosing brand colours for print (your brand guidelines should include both RGB and CMYK values)
• Export as a high-resolution PDF with fonts embedded
• Check our artwork guidelines for file specifications

If you have already read our guide on how to set up print-ready artwork, you will know that colour mode is just one part of the puzzle. Bleed, resolution, and font embedding all matter too. But getting the colour mode right is the single most common fix that improves print quality overnight.

Still Not Sure?

If you are not confident about converting your files, just send them to us as they are. We check every file before printing and will flag any issues. We would rather spend two minutes on a quick email than have you receive a print job you are not happy with.