Delta-E Calculator
Perceptual color difference — CIE76, CIE94 and CIEDE2000.
Overview
The Delta-E Calculator quantifies the perceptual difference between two colours using the three industry-standard CIE formulas: CIE76 (the original Euclidean distance in Lab), CIE94 (weighted for textile work) and CIEDE2000 (the modern reference that handles blue and grey better). Paste two hex codes and the tool reports all three values along with a plain-English interpretation.
It is used in brand quality control, comparing print proofs against a master, validating that a CSS rebuild matches an image asset, and tuning palette tolerances for automated colour pickers. Delta-E is the universal yardstick when "close enough" needs to become a number.
How it works
Both inputs are converted to CIE Lab via sRGB → linear RGB → XYZ → Lab using the D65 illuminant and 2° observer. CIE76 then computes the Euclidean distance sqrt((ΔL)² + (Δa)² + (Δb)²) directly in Lab. CIE94 adjusts the chroma and hue terms with weighting factors tuned for graphic arts, and CIEDE2000 layers additional corrections for the non-uniformity of Lab around neutrals and in the blue region.
CIEDE2000 is the most accurate and the only one of the three that aligns closely with paired-comparison perception experiments, but it is also the most expensive to compute. CIE76 remains useful as a fast first pass when scanning large numbers of colour pairs.
Examples
#ffffff vs #fefefe → ΔE76 0.7 ΔE94 0.7 ΔE00 0.7 (imperceptible)
#ff0000 vs #ff3300 → ΔE76 11.4 ΔE94 4.0 ΔE00 4.4 (noticeable)
#3366cc vs #336699 → ΔE76 16.0 ΔE94 11.2 ΔE00 9.8 (clearly different)
#000000 vs #ffffff → ΔE76 100 ΔE94 100 ΔE00 100 (max)
FAQ
What ΔE value counts as "the same colour"?
Common rules of thumb: ΔE below 1 is imperceptible to most people, 1–2 perceptible on careful comparison, 2–10 perceptible at a glance, and 10+ obviously different. The exact thresholds depend on the viewing condition.
Which formula should I use?
CIEDE2000 for any modern brand-tolerance work. CIE76 is fine for ballpark comparisons and is what most older systems still report. CIE94 is mainly retained for legacy textile and graphic-arts tooling.
Why does ΔE76 give bigger numbers than ΔE00?
The 1976 formula treats all hue regions equally, so areas where Lab is perceptually non-uniform (especially saturated blues) are exaggerated. ΔE2000 corrects this and typically returns smaller, more realistic values.
Can I use ΔE for colorblind-friendly palette design?
ΔE is computed in standard Lab and ignores colour-vision deficiencies. For colourblind palettes, simulate the deficiency first and then compute ΔE between the simulated entries.
Does the calculator support OKLab Delta-E?
OKLab is a separate space and its Delta-E (called ΔE-OK) is computed with the same Euclidean formula in OKLab coordinates. It is sometimes used in modern design tools as a simpler alternative to ΔE2000.