Brand Colours Explained: HEX, RGB, CMYK and Pantone

Here's a problem almost every brand hits eventually: the blue on the website looks crisp and electric, the same blue on the printed brochure looks muddy and grey, and the branded tote bag came back looking almost purple. Nobody did anything obviously wrong. The colour was "the same" in every file. And yet three surfaces produced three different blues.

Understanding your brand colours means understanding why that happens — and how to define colour precisely enough that it doesn't. This guide explains HEX, RGB, CMYK and Pantone, how they relate, and how to specify tolerances so "our blue" means one thing everywhere.

Four ways to describe the same colour

A colour value is just a set of instructions for producing a colour in a particular medium. Different media need different instructions.

RGB (Red, Green, Blue) is additive colour — light emitted by a screen. Each channel runs 0–255. Your brand navy might be RGB(26, 60, 110). Because it starts from black and adds light, RGB can produce bright, saturated colours that print simply cannot.

HEX is the same RGB values written in base-16 for the web. RGB(26, 60, 110) becomes #1A3C6E: 1A is 26, 3C is 60, 6E is 110. HEX and RGB are two notations for one thing. Use HEX in CSS and design tools; it's your default for anything on a screen.

CMYK (Cyan, Magenta, Yellow, Key/black) is subtractive colour — ink on paper absorbing light. Each channel is a percentage, 0–100. Our navy might print as roughly CMYK(85, 65, 20, 5). Because ink can only subtract from white paper, the CMYK gamut is smaller than RGB — which is exactly why vivid screen colours dull down in print.

Pantone (PMS) is a proprietary system of pre-mixed spot inks, each with a fixed recipe — for example PMS 2955 C. Instead of building a colour from four inks, the printer uses one ready-made ink, so it's consistent from run to run and print shop to print shop. Pantone is the gold standard for logos, packaging and merchandise where colour must not vary.

Why the conversions never match perfectly

The core issue is gamut — the range of colours a medium can physically produce. RGB screens can show colours that CMYK ink can't reach, and Pantone spot inks can hit colours that neither four-colour print nor some screens can. Converting between them is not lossless arithmetic; it's an approximation that maps a colour into whatever the target medium can manage.

That's why you should never treat an automatic conversion as final. A HEX-to-CMYK conversion from a design app is a starting point, not a spec. Always get a printed proof and, for spot colour, check against a physical Pantone chip under controlled lighting — Pantone recommends a D50 (5000K) light booth, because the same ink looks different under warm office light versus daylight.

How to specify a brand colour properly

For every colour in your palette, publish all four values plus context:

• Name: Brand Navy
• HEX: #1A3C6E (web, digital)
• RGB: 26, 60, 110 (screens, video)
• CMYK: 85, 65, 20, 5 (coated stock — confirm with your printer)
• Pantone: 2955 C (spot printing, merchandise)

Note the "C" in the Pantone reference: it means Coated stock. The same ink on Uncoated (U) paper looks different, so specify the finish. And add the caveat that CMYK values should be confirmed against a proof for each paper and press, because they genuinely will shift.

Defining colours this thoroughly is a core part of any real set of brand guidelines — and it's what makes the difference between a palette that holds and one that quietly drifts.

Set a tolerance with ΔE

"Close enough" needs a number, or every discussion about colour becomes an argument. That number is ΔE (delta-E), a measurement of the perceived difference between two colours in the CIE Lab colour space, which is designed to model how human vision actually works.

A useful rule of thumb:

• ΔE 0–1: a difference the human eye generally cannot detect.
• ΔE 1–2: perceptible only on close side-by-side inspection.
• ΔE 2–3.5: noticeable to an attentive viewer.
• ΔE > 5: obviously a different colour.

For brand colour, a tolerance of ΔE ≤ 2.0 is a sensible, defensible standard for critical applications like the logo, with a slightly looser ΔE ≤ 3 acceptable on large printed areas where press variation is higher. Writing this into your guidelines turns colour from a matter of opinion into a measurement.

Why measuring colour by eye fails

The trouble is that people can't reliably judge ΔE by looking. Two blues at ΔE 3 look "the same" to most viewers glancing quickly, yet that drift, repeated across every touchpoint, is exactly how a brand loses its distinctive colour. And nobody can eyeball whether a logo on a partner's live web page is your #1A3C6E or a lookalike #1B3F72.

This is where HasMyBrandChanged helps. You set your approved colours once in a Brand Blueprint, then check any uploaded asset — or a live web page — against it in under a minute. Colour is measured precisely with CIE Lab ΔE rather than guessed, so a shade that's drifted beyond your tolerance is flagged and drawn directly on the artwork, with the exact ΔE shown. Logo geometry is checked against your master file, and type and layout are AI-reviewed with confidence levels.

If you can't measure the difference, you can't defend the colour.

Common mistakes to avoid

• Specifying only HEX. Fine for the web, useless for your printer. Publish all four spaces.
• Trusting auto-conversion for print. Always proof.
• Ignoring paper finish. Coated vs uncoated Pantone can look markedly different.
• No tolerance. Without a ΔE ceiling, "on brand" is just an opinion.
• Forgetting merchandise. Embroidery, powder-coating and vinyl each have their own colour behaviour — supply a Pantone reference so suppliers match to a physical standard.

Colour is one of the fastest signals of a brand, and one of the first things to drift. Nail down every value, set a ΔE tolerance, proof your prints, and check your live assets. For the bigger picture on holding colour and everything else together, see brand consistency across channels.

Want to know if your brand colours are drifting right now? Set your palette as a Brand Blueprint and measure every asset by ΔE.