Delta E Calculator
ΔE (CIEDE2000)
9.3357
CIEDE2000: 9.3357
CIE94: 8.8089
CIE76: 11.73
Side by side in a UI
Contrast between the two: — full contrast check →
Does the difference survive color blindness?
ΔE recomputed on the simulated pair. If it collapses toward 0 for a deficiency, those users can't tell your two colors apart — same matrices as the simulator.
How Delta E is measured
Delta E is the Euclidean distance between two colors in CIELAB space, a color space designed so that equal distances correspond to roughly equal perceived differences — unlike RGB or HSL, where the same numeric distance can look wildly different depending on where you are in the space. CIE76 is the original, simplest Delta E formula. Later refinements (CIE94, CIEDE2000) correct for some perceptual non-uniformities but are more complex to compute.
What counts as "close enough" by industry
Tolerances differ by field because the stakes differ. Print production commonly works to a ΔE tolerance around 2 against a proof (the "just noticeable difference" band), with brand-critical spot colors held tighter. Display calibration reviews often treat average ΔE under 1–2 as excellent. In UI work the question usually inverts — you're checking whether two supposedly identical tokens drifted apart (anything > 1 between "the same" brand color in two files is a bug), or whether two supposedly different state colors are distinguishable (aim well above the JND, and check the color-blindness row above). One caveat that surprises people: ΔE describes the color values, not your screen — an uncalibrated monitor shifts both colors together, so the ΔE between them barely changes even though both look different from the "true" color.
Frequently asked questions
Under 1.0 is imperceptible to the human eye. Under 2.3 is a widely used industry threshold for an acceptable match in printing and manufacturing (a 'just noticeable difference').
CIEDE2000 (the starred default) is the current standard and the most perceptually accurate, especially for saturated colors and blues — our implementation is verified against the published Sharma, Wu & Dalal reference dataset. CIE76 is the simplest and still fine for rough design checks; CIE94 sits between them and appears in older graphic-arts workflows. When formulas disagree, trust CIEDE2000.
CIE76 measures straight-line distance in LAB, but LAB isn't perfectly uniform — differences in saturated regions look smaller than the raw distance suggests. CIE94 and CIEDE2000 apply weighting functions (and, in CIEDE2000, a rotation correction in the blue region) to compensate. The more saturated your colors, the more the formulas diverge.
Practically no — different sRGB values map to different LAB coordinates, so a genuine zero means identical colors. But rounding can make very close neighbors (like #000000 and #010101) land under 0.5, which is far below anything an eye can detect anyway.
Not the number itself — Delta E here is computed from the color values, assuming standard sRGB. An uncalibrated screen shifts how both colors look to you, but it shifts them together, so their difference stays roughly the same. Calibration matters when you need the on-screen colors to match a physical print.
Because RGB distance doesn't track perception: moving 20 units in RGB is invisible in some regions of the space and obvious in others. LAB was designed so that equal distances feel like roughly equal differences, which is the entire point of a difference metric. The pipeline diagram above shows the conversion chain.
Not always — that's what the simulation row checks. Two colors distinguished mainly by red-green hue can have a healthy Delta E for typical vision yet collapse to near zero under protanopia or deuteranopia. If your two colors encode different meanings, check that row before shipping.
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