What is Delta E (ΔE)?

When our colour match compares your Pantone or brand colour with a chip in our printed Process Colour Guide, it gives each match a ΔE value. A ΔE of 0 is identical. A ΔE of 1 is about the smallest difference a trained eye can see with the two colours side by side. Above 5, most people would call them different colours.

What the numbers mean

Screens can’t show printed colour exactly, so these pairs are a guide to the size of each step, not a proof. The printed guide is the real reference.

How close is close enough?

• Under 2: order by the chip’s page, row and column, or its CMYK values, and expect a match.
• 2 to 5: look at the chip in the printed guide before you decide. For many jobs it’s fine; for a brand colour you may want closer.
• 5 or more: the colour is outside what CMYK can print on that paper — common with bright oranges, greens, blues and fluorescents. For a true match, print it as a spot (Pantone) ink: we mix Pantone inks in-house and run them on our two-colour press. Expect the cost of the job to go up, sometimes considerably: the ink has to be mixed and matched to your colour by hand, which takes time, and it usually needs an extra press run with its own plates, set-up and wash-up — most noticeable on short runs. Ask us for a price before you commit to the colour.

Why the same colour scores differently on coated and uncoated paper

Uncoated paper soaks the ink in, so every colour prints a little softer and darker than on coated stock. That’s why Pantone publishes separate C (coated) and U (uncoated) values, and why our colour match asks which paper you’re printing on. A colour that is a close match on gloss can be out of reach on bond.

Press variation

No press prints every sheet identically. Ink, paper batch, humidity and run length all move colour a little; on a well-run press, sheets typically stay within about 2 to 3 ΔE of each other. So a match under 2 is about as close as printing gets — chasing a smaller number won’t show on paper.

Which Delta E we use

There are several formulas for ΔE. We use CIEDE2000 (ΔE₀₀), the newest formula from the International Commission on Illumination (CIE), published as ISO/CIE 11664-6. It was built to track what people actually see more closely than the formulas before it. The older ΔE₇₆ formula gives larger numbers for bright, saturated colours, so if another tool quotes a bigger ΔE for the same pair, it’s probably using the older formula.

Our chip values are predicted from industry-standard press conditions (GRACoL coated and US sheetfed uncoated) They haven’t been measured off the printed guide yet, so treat the ΔE as a close estimate and check the chip itself before you decide.

Match a colour More print resources