How shade matching works
Every match Shadewell publishes is a measurement. This page explains what is being measured, what the numbers mean, and where the method stops being reliable.
Do shade numbers mean the same thing across brands?
No, and this is the whole problem. Each brand numbers its own range independently. There is no industry standard mapping one range onto another, so "Fenty 240" and "Estée Lauder 2C1" have no official relationship whatsoever — a brand can call a shade whatever it likes.
What brands do publish is colour. Every shade in this catalog — 553 of them across 15 brands — is stored as a CIELAB value, a coordinate in a colour space designed so that distance corresponds to how different two colours look to a human eye. Once two shades are expressed as coordinates, the distance between them is arithmetic rather than opinion.
What is Delta E?
Delta E (written ΔE) is the distance between two colours. Shadewell uses CIEDE2000, the current CIE standard formula, which corrects the older Euclidean measure for the fact that the eye is far more sensitive to some kinds of difference than others.
The bands used throughout this site:
- Under ΔE 2 — excellent. Most people would not see the difference on skin.
- ΔE 2 to 4 — good. A visible difference under close inspection, but a workable substitute.
- ΔE 4 to 7 — approximate. A starting point, not a swap. Expect to see it in daylight.
- ΔE 7 and above — not shown. Omitted entirely rather than presented as a match.
These are the same thresholds the Shadewell iOS app uses, computed with the same formula, so a number here and a number in the app always agree.
How accurate is cross-brand matching, really?
Less accurate than most shade-finder tools imply. Across every possible cross-brand pairing in this catalog, 16% of closest matches land in the excellent band, 38% in good, and 46% are only approximate. Roughly a fifth of all pairings have no match close enough to publish at all.
That is not a flaw in the measurement — it is what the market actually looks like. Brands do not coordinate their ranges, so for any given shade there is often simply nothing equivalent elsewhere. Sites that always produce a confident answer are hiding this; Shadewell states the distance and lets you decide.
Why undertone is scored separately
Undertone is the colour cast underneath depth — warm, cool, neutral or olive. Two shades can sit at nearly the same lightness and still look wrong on the same face because their undertones disagree.
So ranking does not use raw distance alone. A candidate whose undertone differs is penalised before ranking: 1.5 for an adjacent undertone, 4.0 for an opposing one (warm against cool, or olive against cool). The displayed ΔE is always the true measured distance; the penalty only affects which match is shown first.
Where this method stops working
Colour is not the whole story, and it is worth being clear about what these numbers cannot tell you. Finish changes how a shade reads — a matte and a luminous foundation at identical ΔE will not look identical on skin. Many foundations oxidise after application and drift warmer over a few hours. Coverage changes how much of your own tone shows through.
Depth coverage is also uneven. This catalog spans depth levels 3 to 10, and ranges thin out at both ends, so matches for very fair and very deep shades have fewer candidates to choose from. Olive is the scarcest undertone of all: 28 shades out of 553.
A measured match narrows 553 shades down to a handful worth trying. It does not replace seeing a shade on your own skin, in daylight, after it has settled.