Why INCI Order Tells You More Than the Ingredients List
Published by AmpleLab Research
Most people buying a cosmetic product read the marketing copy on the front. Some read the "key ingredients" callout on the back panel. Very few read the full INCI list in small print, and fewer still know how to interpret it. This is a meaningful gap, because the INCI list is the most truthful part of a cosmetic label. It is governed by law, not by the brand's marketing department, and it contains one piece of structural information that marketing copy almost never provides: a ranked indication of what is actually in the product, in what relative quantities.
This article explains how the INCI list works, how to read it, what it can and cannot tell you, and why it is particularly useful when evaluating products that make claims about active ingredients like copper peptides.
INCI stands for International Nomenclature of Cosmetic Ingredients. It is a standardised naming system maintained by the Personal Care Products Council (PCPC) and adopted globally, which assigns a single fixed name to each cosmetic ingredient regardless of which brand uses it or what trade name they give it in their marketing copy. When a manufacturer sells a product in the UK or EU, they are required by law to list all ingredients on the label using INCI nomenclature, in a specific order.
This standardisation matters because it removes brand discretion from ingredient identification. A brand can call their product "Bio-Active Copper Complex" on the front label, but the INCI list on the back must read "Copper Tripeptide-1" if that is what the ingredient is. INCI names are fixed, independently maintained, and not subject to trademark or brand variation. They are the same whether you are reading a £12 bottle or a £120 one.
Under UK and EU cosmetics regulation, ingredients must be listed in descending order of weight at the time they are incorporated into the formula. The first ingredient is the most abundant by weight. The second is the next most abundant. And so on, with one important exception covered below.
This rule is not a guideline. It is a legal requirement under UK Cosmetic Products Enforcement Regulations (implementing EU Regulation 1223/2009, retained in UK law). A brand cannot legally list their star active second if it is actually the eighth most abundant ingredient in the formula.
The core principle
First ingredient = highest concentration. Last ingredient (before colorants and fragrances) = lowest concentration among ingredients present above the threshold. The INCI list is a ranked list, not just a list of things that are "in there."
The regulation contains one exception to the descending order requirement: ingredients present at a concentration of 1% or less may be listed in any order after all ingredients present at more than 1%. Colorants, fragrance components, and parfum follow their own listing rules and typically appear last.
This threshold has two practical implications. First, it creates a visible division in any INCI list: ingredients above 1% are ranked by concentration; ingredients at or below 1% are unranked among themselves. Second, it means that among the ingredients listed after the main carrier components, you cannot determine which is at 0.9% and which is at 0.001%; they can be listed in any order the brand chooses.
What you can do is use known benchmarks to find the approximate dividing line. Preservative systems (phenoxyethanol is typically used at around 0.7–1%, ethylhexylglycerin at around 0.08–0.1%) and sodium hyaluronate (usually 0.1–0.3% in a serum) are common ingredients whose typical use concentrations are reasonably well-documented. An ingredient appearing before these is very likely above 1%. An ingredient appearing after them could be anywhere from 0.9% to a trace.
AmpleLab's GHK-Cu serum carries the following INCI list:
Reading this list against the descending order rule tells you several things directly: water is the primary carrier; glycerin is present at a meaningful humectant concentration (3%); the active, Copper Tripeptide-1, appears third, above both the preservative system and the sodium hyaluronate. The positioning of the active above phenoxyethanol, which is typically used at around 0.7–1%, places the active at or above that level. In this case AmpleLab also states the concentration directly on the label (1%), removing any ambiguity.
One of the most useful things the INCI system provides is a way to cut through trade naming. Brands give their ingredients commercial names; the INCI list gives you the standardised name regardless. These are not always the same thing.
The hyaluronic acid example is a useful illustration: "hyaluronic acid" is a common marketing term, but the INCI list almost always reads "Sodium Hyaluronate," which is the more stable sodium salt form used in most formulations. A product saying "contains hyaluronic acid" is typically referring to sodium hyaluronate. This is not deceptive, but it does illustrate that marketing language and INCI language are not interchangeable, and only the INCI list tells you what is actually in the bottle.
The descending order rule makes INCI position a meaningful signal when evaluating how seriously a product takes its claimed active. A product marketed as a "copper peptide serum" where Copper Tripeptide-1 appears as the tenth ingredient, after several solvents, thickeners, and emulsifiers, is making a very different formulation commitment from one where it appears third. Both products can say "contains copper peptides." Only the INCI list tells you where the commitment actually sits.
Many commercially available formulations and some experimental work focus on concentrations around the 1% range, though the published literature spans a broader range depending on the model, formulation, and endpoint studied. A product where the copper peptide appears after the preservative system is very likely below 1%, and may be at a small fraction of that. Whether that matters depends on whether you believe the product's efficacy claims are grounded in the research, or whether you are paying for positioning.
The same framework applies to any active. Retinol listed as the 15th ingredient in a "retinol serum" may not correspond to the concentrations commonly evaluated in clinical studies. Niacinamide appearing after sodium hyaluronate in a "10% niacinamide" product is an obvious contradiction. INCI order makes these contradictions visible to anyone who knows to look for them. The relationship between concentration, research, and label claims is covered in more depth in the article on copper peptide concentration and what most labels don't tell you.
INCI order is useful but not complete. Its limitations are worth being clear about.
Knowing an active is third tells you it is more abundant than the fourth ingredient but not exactly how much more. Glycerin at position two could be 1% or 10%. You can narrow the range using benchmark ingredients but you cannot get an exact figure from INCI order alone: only voluntary concentration disclosure on the label, a Certificate of Analysis, or independent testing provides that.
Among the ingredients present at or below 1%, the brand can list them in any order. A brand could technically list their below-1% "hero ingredient" before their preservative in the sub-1% section and give an impression of higher positioning. The benchmark ingredient approach helps to identify approximately where the 1% dividing line sits, but it is not foolproof.
Two products can both list "Copper Tripeptide-1" at the same INCI position with very different actual purity levels of the raw material. A 95% purity ingredient and a 60% purity ingredient of the same compound both read the same on the INCI list. Purity is only visible from the supplier's Certificate of Analysis.
The INCI list is also where glycol presence becomes visible. Propylene glycol, butylene glycol, and related compounds are commonly used as solvents, humectants and, in some formulations, penetration enhancers. In many formulas, these appear as the second or third ingredient, which under the descending order rule means they are present at substantial concentrations, not trace amounts. A product listing "Propylene Glycol" at position two is using it as a primary carrier component, not a minor co-solvent.
When AmpleLab describes its formulas as glycol-free, this is a verifiable claim against the INCI list: propylene glycol, butylene glycol, and related glycol compounds do not appear anywhere in the ingredient list. The INCI list is where such claims either hold up or fall apart. The rationale for the glycol-free approach, and its relevance to microneedling compatibility and sensitivity, is covered in the product pages for the 1% AHK-Cu Hair and Scalp Serum and 1% GHK-Cu Face and Skin Serum.
A practical reading process for evaluating any cosmetic that makes active ingredient claims:
Use the marketing name to identify what the brand is claiming, then find the corresponding INCI name in the full ingredient list. "Copper peptide" means Copper Tripeptide-1 or Copper Tripeptide-3. "Vitamin C" could mean Ascorbic Acid, Sodium Ascorbyl Phosphate, Ascorbyl Glucoside, or several other forms. Find the actual INCI entry.
Does the active appear before or after phenoxyethanol or similar preservatives? Before or after sodium hyaluronate? Before or after butylene glycol or propylene glycol (if present)? Anything appearing before the preservative system is likely above 0.7–1%. Anything appearing after sodium hyaluronate is likely below 0.3%.
Some brands voluntarily state the concentration of key actives, either on the label, in the product description, or in supporting documentation. This removes the inference step entirely. When a brand states "1% Copper Tripeptide-1" and the INCI list shows Copper Tripeptide-1 in the third position above the preservative, the two signals corroborate each other. When they don't: when a brand claims a high concentration but the active appears buried in the list, that discrepancy is worth noting.
The ingredients immediately below water tell you what the primary carrier is. Glycerin is a standard humectant and generally unproblematic. Propylene glycol or butylene glycol high in the list indicates a glycol-heavy carrier, which matters if you are using microneedling or have glycol sensitivities. A simple carrier with a short ingredient list is sometimes easier to evaluate than a complex one.
What does INCI stand for?
International Nomenclature of Cosmetic Ingredients. It is a standardised naming system maintained by the Personal Care Products Council (PCPC) and adopted globally for cosmetic labelling. In the UK and EU, manufacturers are legally required to use INCI names when listing ingredients on cosmetic product labels.
Are ingredients always listed in descending order?
Yes, with one exception: ingredients present at 1% or less may be listed in any order after those present at more than 1%. Colorants may also follow their own listing rules. This means the descending order rule applies reliably to the ingredients making up the bulk of the formula, but the tail end of the list is less informative about relative ranking among low-concentration ingredients.
Why does an INCI list say "Sodium Hyaluronate" when the product claims "hyaluronic acid"?
Sodium hyaluronate is the sodium salt of hyaluronic acid and the form most commonly used in formulations for stability reasons. "Hyaluronic acid" is the marketing convention; "Sodium Hyaluronate" is the INCI name for the same functional ingredient. Both attract water and act as humectants. The distinction only matters if you are specifically looking for the free acid form, which is less common in finished products.
How do I find the INCI name for an ingredient a brand is marketing?
The official CosIng database, maintained by the EU Commission at ec.europa.eu/growth/tools-databases/cosing, lists INCI names for all registered cosmetic ingredients. Searching a common name, trade name, or CAS number will typically return the corresponding INCI name. For copper peptides specifically: GHK-Cu is Copper Tripeptide-1; AHK-Cu is Copper Tripeptide-3.
If a brand doesn't disclose the exact percentage of an active, is that suspicious?
Not necessarily. Concentration disclosure is voluntary, not mandatory under UK or EU cosmetics regulations. Most brands do not disclose percentages. What should prompt further scrutiny is a mismatch between the marketing claim ("high-concentration copper peptide serum") and the INCI position of the active (appearing after the preservative system, suggesting below 1%). The INCI list gives you enough information to evaluate plausibility even without a stated percentage.
Does AmpleLab disclose ingredient concentrations?
Yes. AmpleLab states the active concentration directly on the label for all current products: 1% for both GHK-Cu and AHK-Cu serums, and 2% for the 2dDR Hair Serum. This is consistent with brand positioning around formulation transparency; the INCI list and stated concentration should agree with each other, and both are verifiable. For an applied breakdown of how the GHK-Cu buyers guide and AHK-Cu buyers guide use INCI position as part of their evaluation criteria, both are worth reading alongside this article.
Cosmetic Products Enforcement Regulations 2013 (SI 2013/1478)
UK legislation implementing cosmetic product safety and labelling requirements, including the INCI listing rules.
Regulation (EC) No 1223/2009 of the European Parliament and of the Council on Cosmetic Products
The source EU regulation, Article 19 covering labelling requirements and Annex I on the format of information. Retained in UK law post-Brexit.
CosIng: EU Commission Cosmetics Ingredients Database
The official database for INCI names, CAS numbers, and ingredient functions for registered cosmetic ingredients.
This article is provided for educational purposes. The INCI labelling requirements described reflect UK and EU cosmetics regulations at the time of writing. AmpleLab products are cosmetic formulations registered under the UK Cosmetic Product Notification Portal (CPNP/SCPN).
AmpleLab.