Field Notes
Comedogenic ratings: what the numbers actually mean
A comedogenic rating scores one raw ingredient in a test that was never about finished products. Where the 0-5 scale came from, why sources disagree, and what to weigh instead.
Direct answer
A comedogenic rating is a 0–5 number attached to a single raw ingredient, mostly derived from mid-century testing that applied concentrated substances to animal ear models. It was never a measurement of how a finished product behaves on a human face, and it does not become one by being repeated.
That is not an argument for ignoring congestion. It is an argument for treating the number as a weak prior and your own history as the strong one.
Where the numbers came from
The scale reflects a specific experimental setup: an isolated ingredient, at a high concentration, on a model chosen because it clogs readily. Those choices made sense for screening raw materials. They do not transfer to a moisturiser where the same ingredient sits at two percent alongside twenty others.
Three things break the translation:
- Concentration. An ingredient at 100 percent and the same ingredient at two percent are not the same exposure.
- Formulation. What an ingredient is combined with changes how it sits on skin, how much stays there, and how it is delivered.
- The face it lands on. The model was chosen for sensitivity to clogging. Your skin was not.
None of this makes the ratings fabricated. It makes them a screening tool being used as a verdict.
Why the same ingredient carries different numbers
If you have looked up one ingredient across several sites and found different values, that is not a mistake on someone's part. There is no single authority publishing a canonical list. Numbers circulate, get copied, get adjusted, and diverge.
Shea butter, castor oil, jojoba oil, argan oil, coconut oil, olive oil and palmitic acid all have widely quoted ratings that vary by source. Ingredients that appear mainly as formulation components rather than headline actives — ethylhexyl palmitate is the common example — carry numbers that many people encounter without any sense of how much of it is actually in the product they are holding.
A number with no stated source, no stated concentration and no stated method is not data you can act on. It is a number.
What a checker can and cannot tell you
Tools that read a full ingredient list are genuinely useful, and it is worth being precise about what the usefulness is.
A checker can tell you what is actually in a product, in the order the list declares, which is more than most marketing will. It can flag ingredients you have personally reacted to before. It can compare two products you are choosing between and show you where they differ. It can find something you already know you avoid without you reading forty INCI names by eye.
What it cannot do is predict whether a given formula will clog your pores. No tool has that information, because the thing that determines it — your skin, this formula, this frequency — is not in the ingredient list. Any tool that returns a confident pore-clogging verdict from a list of names is telling you something it cannot know.
Droplet's ingredient checker is built on that distinction. It reads the label and remembers what you reacted to. It does not score products, and it does not run a blacklist.
The substitution that actually works
Replace the general question with a personal one.
"Is this ingredient comedogenic" has no usable answer. "Have heavy occlusive products congested my skin before" usually does, and you are the only person who holds it. If three rich balms have broken you out and one has not, the difference between them is worth more than any rating.
That personal record is not something you can look up. It has to be kept:
- Note which products you have congested from, not just which ingredients.
- Note where on your face it happened, since congestion has geography.
- Note how long you used it before it showed, because a rating implies an immediacy that congestion rarely has.
- Note what else was in the routine at the time.
After a handful of entries this beats any published scale, because it is measuring the thing you actually want to predict.
How to read a product when you are prone to congestion
Practical order of operations, using the label rather than the number:
- Read the full INCI list, not the front of the box. "Non-comedogenic" is an unregulated marketing term and carries no defined testing standard.
- Look at position. Ingredients are listed in descending order down to one percent. Something near the end is present in a small amount.
- Compare against your own history before comparing against a chart.
- Introduce it on one area first, and hold it long enough to see a pattern.
- Change one product at a time, so a result is attributable.
- Give it several weeks. Congestion that shows up in a day is usually irritation wearing congestion's clothes.
Bottom line
Comedogenic ratings are a screening artefact from a different kind of test, repeated widely enough to feel authoritative. They are worth knowing about mainly so you can recognise when a confident number is being handed to you with no method behind it.
Read the whole list, weigh your own history above the chart, change one thing at a time, and let the record you keep do the predicting.
Source notes
This article is about how a rating scale is used, not a safety assessment of any ingredient. Public references relied on here:
No claim here is an efficacy finding or a recommendation for or against a brand.
Checklist
- Treat a 0–5 rating as a weak prior, never a verdict on a finished product.
- Expect the same ingredient to carry different numbers across sources.
- Check concentration and position on the list before reacting to a name.
- Remember "non-comedogenic" on packaging is unregulated.
- Use a checker to read labels and recall your reactions, not to predict clogging.
- Keep a personal record of what congested you, where, and after how long.
- Introduce one product at a time and give it weeks, not days.
Before the product touches your skin, check the label.
Droplet Skincare is the official home of Droplet. Droplet scans labels, checks claims, weighs profile fit, and turns product evidence into routine memory without ads or sponsored ranking.
Frequently asked questions
What does a comedogenic rating actually measure?
It reflects a mid-century screening setup: an isolated ingredient, at high concentration, applied to an animal ear model chosen because it clogs readily. That was a reasonable way to screen raw materials. It was never a measurement of how a finished product behaves on a human face, and concentration, formulation and your own skin all break the translation.
Why do different sites give the same ingredient different comedogenic ratings?
Because no single authority publishes a canonical list. Numbers circulate between sources, get copied and adjusted, and diverge. A rating quoted with no stated source, no concentration and no method is not data you can act on.
Can an ingredient checker tell me if a product will clog my pores?
No tool has that information, because what determines it is your skin, this specific formula and how often you use it, none of which appear in an ingredient list. A checker is genuinely useful for reading what is actually in a product, flagging ingredients you have reacted to before, and comparing two products. Treat any confident pore-clogging verdict from a list of names with suspicion.
Does non-comedogenic on the packaging mean anything?
It is an unregulated marketing term with no defined testing standard behind it. It is not a claim you can rely on the way you can rely on the ingredient list, which has to be declared in descending order of concentration down to one percent.
What should I use instead of comedogenic ratings?
Your own record. Note which products congested you, where on your face, how long you used them first, and what else was in the routine at the time. After a handful of entries that beats any published scale, because it measures the thing you actually want to predict.
This article is informational skincare guidance. It does not provide medical advice, diagnosis, or treatment.