Delta E is a numerical score that tells you how far off a display's colour reproduction is from a laboratory reference standard. It measures the difference between what you see on screen and what the colour should actually look like. A Delta E of 0 means perfect colour accuracy; higher numbers indicate larger, more visible errors.
The scale works like this: a Delta E below 1 is imperceptible to the human eye. Between 1 and 3, most people won't notice the difference in everyday use. Above 3, colour shifts become visible, especially to anyone doing photo editing, video work, or graphic design. Professional colour-critical work typically demands a Delta E below 2.
Displays measure Delta E using specialised software that compares hundreds of colour samples across the screen against known reference values. The test accounts for brightness, saturation, and hue. You'll often see results listed as an average (for example, Delta E 1.2) or a maximum value (Delta E 3.8 at the worst point).
For a consumer buying a new monitor, laptop, or tablet, Delta E matters most if you're editing photos, video, or design work. A gaming monitor or general web-browsing device doesn't need extreme colour accuracy. Budget displays might score Delta E 4 to 6. Mid-range models typically hit 2 to 3. Professional monitors and high-end laptops often achieve below 1. Check the manufacturer's specifications or independent reviews for Delta E figures before purchase if colour accuracy is important to your work.