Correction

There Is No Standard Behind the Hair-Colour Number Chart

The claim

“A 7.4 is the same copper whichever brand you buy — the numbers are a standard code.”

The short answer

Because nobody owns the chart. The level/tone convention is industry practice, not a standard — no ISO, no annex, no legal definition — so the tone digits genuinely differ between manufacturers.

Evidence status

Settled

The Cosmetic Record · Published 2026-08-06 · Last checked 2026-08-06 · 15 sources · Corrections: none

1. What the two halves of the number are supposed to mean

Three manufacturers print the same shape on the tube: a digit, a separator, then one or two more digits. They also agree on what the positions are for. L'Oréal Professionnel's Majirel chart labels them Level of color, Primary tone of color and Secondary tone of color.¹ Wella's Koleston Perfect booklet sets out the same three positions against the worked example 4/71 as Depth of color, Major tone of color and Minor tone of color.² Schwarzkopf's IGORA ROYAL chart carries the same three positions as a labelled diagram — Base Level in front of the dash, Primary Tone Direction and Secondary Tone Direction after it — under the sentence “Our numbering system is based on a combination of numbers. The number(s) after the dash also have a corresponding letter that indicates the tone direction.”³

The depth digit is the half that behaves. Schwarzkopf prints the ladder under the heading Level of Depth: 1 black, 3 dark brown, 5 light brown, 7 medium blonde, 9 extra light blonde, 10 ultra blonde — no 2 in the list — with separate high-lift series at 10- and 12-.³ Majirel's rows run the same way, from 1/1N to 10/10N.¹ A reader who treats the first digit as a rough depth is not being misled. It is everything after the separator that fails.

2. Nobody owns this chart — we went looking for the standards body

Salon education calls the convention the “International Colour Chart”, usually abbreviated ICC, and the name does a lot of work: it implies an issuing body, a document number and a revision date. We looked for all three and found none, and this is the finding rather than a gap in it.

Cosmetics do have a technical committee at the International Organization for Standardization: ISO/TC 217. Its catalogue carries 52 published entries, 41 of them standalone documents and 11 amendments to those documents. They are microbiological methods, analytical methods, sun-protection test methods, packaging and labelling (ISO 22715:2006), good manufacturing practice (ISO 22716:2007) and guidelines on what may be called a natural or organic ingredient (ISO 16128-1 and -2). Not one concerns hair colour, shade nomenclature or colour classification.⁴ At European level, CEN/TC 392 “Cosmetics” divides its work between three working groups — analytical methods, microbiological methods, and efficacy including sun protection products. Its business plan does not enumerate work items, and says so; but neither its scope nor any working-group title touches shade naming.⁵

Nor is the numbering defined in law. Regulation (EC) No 1223/2009 restricts hair dye substances by name and concentration and prescribes label warnings word for word, and says nothing about what a digit means⁹; neither does Brazil's cosmetics labelling rule, nor the United States provision that exempts coal-tar hair dye from the adulteration section of the Federal Food, Drug, and Cosmetic Act.¹²¹⁴ What we are looking at is a trade convention, and conventions drift.

3. Why the tone digits diverge, and which diverge most

Each of the three companies publishes its own key. Set side by side, the keys disagree from the second digit onward, and they disagree most precisely where a reader is most likely to be shopping across brands — in the warm half of the wheel.

Sources for the three columns, in order: the Majirel chart's own tone key¹; the Koleston Perfect tone numbering system²; the IGORA ROYAL number-and-letter tone key.³ The Wella column is the oldest of the three: its tone words come from a booklet file-dated 2015, and the leaflet Wella publishes now keeps the same depth/tone code without printing a word against each digit.¹⁵

Copper is the clearest case, and it is why this belief is worth correcting. A 7.4 in Majirel is a level-7 copper — the chart prints it as 7.4/7C, in the column headed Coppers.¹ The same digit in Koleston Perfect is warm red, and copper is not a discrete tone digit in that key at all.² In IGORA ROYAL, -4 is beige, in Schwarzkopf's own words muted gold, and copper has moved to -7 — the digit L'Oréal uses for green.³ One digit, three answers, every one of them printed by the company that sells the shade.

Notice also what L'Oréal does on its American chart: every shade carries two codes, the European number and a letter code, 7.4/7C. A convention that needs a translation printed beside it on the same page is not a standard.

4. Underlying pigment: the part of the system that is real

Underneath the numbering there is something that does not vary by brand. Hair colour comes from two pigments, and a 2023 review of mammalian pigmentation states the position plainly: “The diversity in hair pigmentation relies mainly on the quantity and ratio of the two types of melanin incorporated into the hair shafts, with other physical aspects of hair fibres intervening only as minor or segmental colour modifiers.”⁶ Eumelanin is the brown-black one; pheomelanin is the red-yellow one.

Permanent colour works on both at once. A 2025 review of hair dyes describes the reaction as mixing a precursor and a coupling agent with hydrogen peroxide in an alkaline medium at pH 8 to 10, and notes that “in an alkaline medium, the oxidizing agent lightens melanin, the natural pigment responsible for hair color in the hair shaft”.⁷ Morel and Christie's Chemical Reviews survey of permanent hair dyeing is the standing review of that chemistry; it is paywalled, and we cite it for scope, not for a sentence.⁸ The consequence is that a tone digit is never applied to a blank surface. It is applied to whatever warmth the lift has exposed.

Salon education attaches a fixed sequence to this — red, red-orange, orange, orange-gold, gold, yellow, pale yellow as the hair lightens — and pairs each stage with a depth level. We could not verify this sequence against a peer-reviewed source, and we say so again below.

5. Ruivo dourado, worked

Golden copper is the shade this address was asked about for years, so take it as the worked example. In Majirel's grammar, 7.43 reads as depth 7, primary tone copper, secondary tone gold, and the chart prints it as 7.43/7CG.¹ Reverse the two reflects and you should get 7.34, gold-primary with a copper secondary. That shade does not appear in the level-7 row of the 2025 chart, although 6.34 and 8.34 both do.¹

That absence is the second half of the correction. The code is an index into a catalogue of shades a company actually manufactures, not a coordinate system in which every combination exists. You cannot derive a shade from the notation; you can only look it up.

The depth digit carries the same caution. It describes the intended result, not the hair in front of it, and a permanent colour lightens only so far: in the European Union, hydrogen peroxide in hair products is capped at 12 % present or released — the developer strength sold as 40 volumes.¹⁰ A level-7 golden copper is a description of a level-7 outcome.

6. Where the law does touch the box

The numbering is unregulated. The contents are heavily regulated, and confusing the two is what makes the belief sound plausible.

In the European Union, Annex III of Regulation (EC) No 1223/2009 lists the permitted oxidative dye substances individually. Entry 8a covers p-phenylenediamine and its salts, and its condition of use is quoted here in full:

After mixing under oxidative conditions the maximum concentration applied to hair must not exceed 2 % calculated as free base

Entries 8 and 9a impose the same architecture on other phenylenediamines and on toluene-2,5-diamine, and entry 8b covers eyelash products.⁹ That shared architecture is why a box marked “PPD-free” is not the same as hypoallergenic: the usual substitute sits under the same entry block, at the same limit, carrying the same printed warning. Annex II bans named direct dyes outright — 1236 HC Yellow No 11, 1237 HC Orange No 3, 1238 HC Green No 1 and 1239 HC Red No 8 and its salts.¹¹ Every one of those entries regulates a molecule. None regulates a number.

Brazil is the same shape. Hair colourant is a Grau 2 product — Anexo I, item II, nº 45 of RDC 907/2024 reads Tintura capilar temporária, progressiva ou permanente — and Art. 24, II of the same resolution prescribes the warnings the label must carry, beginning with “CUIDADO. Pode causar irritação na pele ou reação alérgica. Antes de usar, fazer a prova de toque”.¹² The colourant list that governs every other cosmetic explicitly steps around hair:¹³

Art. 9º A lista do Anexo desta Resolução não inclui as substâncias corantes destinadas exclusivamente a tingir os cabelos.

In the United States, coal-tar hair dye is carved out of the adulteration provision of the Federal Food, Drug, and Cosmetic Act altogether, provided the label bears the statutory caution and directions for a preliminary test.¹⁴ Three regimes, three different mechanisms, and not one of them says what 7.4 means.