Perceptual Color Difference
Calculate how different two colors actually look to humans using CIEDE2000 and Delta-E. The accessibility and brand QA tool.
How Different Are Two Colors, Really?
If you ask the average designer whether two slightly different blues look the same, you will get an answer based on intuition and the specific monitor they are looking at. Color science has a better answer: a numerical metric called Delta-E that estimates how different two colors look to the average human eye. A Delta-E value below 1.0 is generally imperceptible, values between 1 and 2.3 are noticeable on direct comparison but not in isolation, values between 2.3 and 5 are clearly distinguishable, and values above 5 are different enough that nobody will mistake one for the other. The metric matters in three concrete scenarios. Brand consistency: a logo color rendered slightly differently across two implementations is a real problem if the Delta-E exceeds 2.3 and a non-issue below 1.0. Accessibility: when picking semantically distinct status colors like success green and warning yellow, you need their Delta-E high enough that color-blind users can still distinguish them through perceptual cues other than hue. Color management: when calibrating between a screen and a print proof, a target Delta-E of 2 or below is the industry standard for an acceptable match.
Four Delta-E Formulas, Which to Use
Color science has refined the Delta-E formula four times since the 1976 original. CIE76 is the simple Euclidean distance in LAB space, fast but inaccurate for saturated colors. CIE94 adjusts for chroma and is the right pick when you need a quick approximation. CIEDE2000 is the modern industry standard, refining CIE94 with hue-rotation and chroma-dependent weighting that better matches human perception, especially in the blue region. Delta-E OK is the latest entry, defined in OKLab in 2020, and is the simplest formula that still gives near-CIEDE2000 accuracy across the gamut. For most workflows in 2026 the right pick is CIEDE2000 for absolute industry comparability or Delta-E OK for modern web work and design system tooling. The tool shows all four side by side so you can see how they diverge for the colors you are comparing.
Practical Thresholds for Each Use Case
For brand color consistency the target is Delta-E below 1.5 on CIEDE2000, which guarantees no visible difference between two implementations of the same brand color across reasonable viewing conditions. For accessibility palette design the target is Delta-E above 8 between any two semantically distinct status colors, which leaves enough perceptual headroom for color-blind viewers. For color management between screen and print the target is Delta-E below 2 on CIEDE2000 for a calibrated proof match. For quality control in manufacturing the target depends on the material: textile printing typically accepts Delta-E up to 3, while automotive paint requires below 1. Use the calculator below to test specific color pairs against these thresholds before shipping or before signing off on a print proof.
Frequently Asked Questions
What does Delta-E actually measure?+
Delta-E measures the perceptual distance between two colors, scaled so that a value of 1.0 is approximately the smallest difference a trained observer can see under controlled conditions. The metric is built on color spaces designed to be perceptually uniform, so a Delta-E of 5 means roughly the same amount of perceptual difference whether the colors are blue, green, or red. This is what makes it useful for cross-hue comparisons that ordinary RGB distances get wrong.
Which Delta-E formula should I use?+
CIEDE2000 for industry-standard color management work and CIE76 only for quick rough checks. Delta-E OK is a great modern alternative for web design system work because the math is simpler and the accuracy is comparable. CIE94 is mostly historical now. The tool shows all four so you can see how they diverge; the divergence is largest for saturated blues.
Is Delta-E below 1.0 really invisible?+
Under controlled conditions with side-by-side comparison and a trained observer, yes. Under everyday viewing conditions on uncalibrated monitors, the practical threshold is closer to Delta-E 2. For brand QA work the standard target is below 2 to give some headroom for the variance in real-world displays.
Can I use Delta-E to verify accessibility?+
Delta-E by itself is not a WCAG accessibility metric, which is contrast ratio. Delta-E is the right metric for the related question of whether two colors are perceptually distinguishable from each other, which matters for color-coded categorical information. Pair Delta-E with the Contrast Checker tool for full accessibility coverage.
Why do screens give different Delta-E results than print?+
Screens emit light and use additive RGB color, while prints reflect light and use subtractive CMYK. The two media reach different parts of the color gamut, so a color that displays cleanly on screen may have a Delta-E of 5 or more against its closest CMYK equivalent. This is why print proofs use Delta-E against a measured reference rather than against the screen original.
How does the tool calculate Delta-E?+
Inputs are converted to OKLab via the culori library at version 4.0.2 under the MIT license, then the four Delta-E formulas are applied to the OKLab representations. CIEDE2000 specifically requires conversion to CIELAB rather than OKLab and the tool handles this internally, so all four formulas receive the appropriate input space for their definition.
Is there a Delta-E target for video and motion work?+
Video standards typically accept higher Delta-E values because color shifts during motion are less visible than on still frames. Broadcast quality control commonly targets Delta-E below 3, with reference HDR work targeting below 2. For social media and web video the practical target is below 5, since heavy compression introduces shifts in that range regardless.
Can I compare more than two colors at once?+
This tool compares exactly two colors at a time, which is the right scope for QA workflows where you are checking a specific pair. For a full palette where you want every pair compared, the Palette Contrast Matrix tool gives a similar grid view for contrast specifically; a perceptual-difference matrix is on the roadmap.
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