What Is Delta E? The Science Behind Paint Color Matching

You've found the perfect Farrow & Ball color — maybe Elephant's Breath, maybe Down Pipe — and now you want to know if you can get the same color from Behr or Sherwin-Williams for a third of the price. The internet will happily give you a list of "dupes," but most of those lists are based on eyeballing paint chips under a store's fluorescent lights. That's not color science. Color science gives you a number: Delta E.

Delta E in One Sentence

Delta E (written ΔE) is a single number that measures the perceptible difference between two colors. A ΔE of 0 means the colors are identical. A ΔE of 1 is the threshold of human perception — trained colorists can just barely tell two colors apart. A ΔE of 5 means the difference is obvious even to an untrained eye. Every number on the PaintDB similar-colors list is a ΔE score. When you see a cross-brand match listed at ΔE 0.5, that means a color lab specialist with the best equipment in the world could barely detect a difference. On your wall, you won't see one.

Why Simple Hex Codes Don't Measure Color Difference

Two paint chips can have hex codes that are mathematically close — say, #CDC3B7 and #CBC6B8 — and look clearly different on a wall. Two other chips can have hex codes that look far apart and look identical in person. That's because the RGB and hex color models are built for screens, not for human perception. A 10-point jump in the red channel doesn't cause the same visual change as a 10-point jump in the blue channel. And a small numerical difference in a near-neutral color reads as more different than the same numerical difference in a saturated color. RGB distance is geometry. Delta E is perception.

How Delta E Is Calculated: The CIEDE2000 Formula

PaintDB calculates Delta E using the CIEDE2000 formula — the industry standard used by paint manufacturers, textile mills, and automotive coatings labs. CIEDE2000 works in the CIE L*a*b* color space, which was engineered to be perceptually uniform: equal numerical steps produce equal perceived differences, unlike RGB. The L* axis measures lightness (0 = black, 100 = white). The a* axis measures green-to-red. The b* axis measures blue-to-yellow. CIEDE2000 then applies correction factors for chroma, hue, and lightness — because human vision is more sensitive to small changes in near-neutral colors than in saturated ones, and more sensitive to lightness differences than hue differences. The result is a single number that correlates closely with what your eye actually sees.

The Delta E Perceptibility Scale

Here's how to read ΔE values in practical terms. ΔE 0: identical — the same color from two different tinting machines on the same day. ΔE 0–1: imperceptible — no human observer can detect a difference, even side by side. ΔE 1–2: just noticeable to a trained colorist under ideal conditions — two colors shown adjacent under standardized D65 lighting in a color booth. On a wall, indistinguishable. ΔE 2–3: a small color difference that most people can see when the chips are placed directly against each other, but not across a room or on separate walls. ΔE 3–5: a visible difference that anyone can see when the colors are directly compared. Still a plausible dupe for most practical purposes. ΔE above 5: clearly different colors. The comparison is more "inspired by" than "equivalent to."

Real Examples: What Delta E Looks Like in Paint

The most instructive way to understand ΔE is to look at actual cross-brand pairs with their measured scores. The following examples are drawn from PaintDB's database, where every similarity score is a true CIEDE2000 calculation.

ΔE 0.5 — SW Agreeable Gray vs. PPG Whiskers

ΔE 0.6 — F&B Elephant's Breath vs. BM Alphano Beige

ΔE 0.4 — F&B Down Pipe vs. SW Roycroft Pewter

ΔE 0.6 — SW Repose Gray vs. BM Apparition

ΔE 0.9 — F&B Hague Blue vs. BM Brush Blue

Why Deep Colors Need a Stricter Standard

You may have noticed that the Hague Blue / Brush Blue pair (ΔE 0.9) carries a caveat that pairs in the ΔE 0.4–0.6 range don't. That's not a mistake in the formula — it's how human perception works. CIEDE2000 actually accounts for this: the same ΔE value represents a slightly larger perceivable difference in dark, low-chroma colors than in light or saturated ones. Dark colors are unforgiving because tiny differences in pigment show up clearly when light hits a wall at an angle. If you're buying a dupe for a deep, moody color like Down Pipe or Hague Blue, favor matches at ΔE 0.5 or below and test a physical sample before committing.

How PaintDB Uses Delta E Across 51,000 Colors

Every color in the PaintDB database has been compared against every other color from all 27 brands using CIEDE2000. That's approximately 1.3 billion pairwise comparisons. The five closest matches are stored in each color's "similar" section, sorted by ΔE ascending. When you open any color page on PaintDB and scroll to "Similar Colors," you're seeing the closest perceptual matches in the entire 51,000-color database — not guesses, not curated editorial, not brand-to-brand conversions — just math. This is the same approach used by the paint industry itself. Benjamin Moore and Sherwin-Williams both use CIEDE2000-based spectrophotometers when they formulate brand equivalents. PaintDB simply makes the scores visible to you.

Practical Rules for Using Delta E When Buying Paint

ΔE under 1: Buy with confidence. This is as close as two different commercial formulations get. ΔE 1–2: Safe for most walls. The difference will not be visible except under a color analyst's controlled comparison. Get a sample if the color is on trim or cabinetry (smaller surfaces magnify subtle differences against adjacent colors). ΔE 2–3: Get a physical sample before committing. On a 12-square-foot painted area the difference will likely be invisible, but on cabinetry or a feature wall it may be perceptible to a careful eye. ΔE 3–5: This is inspiration territory, not equivalence. The two colors belong to the same family and share a mood, but they're not dupes. ΔE above 5: Different colors. Use these only as starting points for further search.

Delta E vs. LRV: Different Measurements, Both Necessary

Delta E and LRV are the two most useful numbers on a PaintDB color page, and they measure different things. Delta E tells you how different two specific colors are from each other. LRV tells you how much light a single color reflects — which determines whether a room feels bright or dim, expansive or intimate. When hunting for a cross-brand dupe, check both: a pair can match closely on ΔE (same color identity) but differ on LRV (one was formulated slightly lighter than the other). A ΔE 0.8 pair with a 3-point LRV difference is almost always a true dupe. A ΔE 0.8 pair with a 10-point LRV difference means one is noticeably lighter — same hue family, different visual weight.

Frequently Asked Questions