What is an IFRA limit, and how should you set your concentration?

You bought a fragrance oil and the supplier told you “you can comfortably use this up to 20%.” For the next oil the same supplier said 12%. Same company, same price bracket. Where does that number come from, who decides it, and how seriously should you take it?

Short answer: the supplier is not making it up. Whichever raw material inside the oil is the most restricted is the one that sets the figure. The long answer is below.

What IFRA actually is

IFRA (the International Fragrance Association) is the industry body that publishes standards for the safe use of fragrance materials. The toxicology work is carried out by a research institute called RIFM, and IFRA turns the findings into a rule: “this material may be present in a leave-on product at no more than this percentage.”

The standard is not a single number. It varies by product category, because what you put on a lip balm and what you add to a household cleaner do not meet the skin in the same way. Perfume, cologne and hair spray — things applied directly to skin and not rinsed off — fall into category 4. If you make perfume at home, that is the line you read.

Why two oils from the same company have different limits

Because the limit looks at what is in the oil, not at its name. Every fragrance oil is itself a blend of dozens of raw materials. The more concentrated a restricted material is inside it — citral, coumarin, eugenol, oakmoss derivatives — the lower the usable percentage of that oil.

This is why generalisations like “citrus always has a low limit” are only half true. Yes, fresh citrus compositions are often heavy in citral and limonene and the limit drops; but another citrus on the same shelf, built from synthetic molecules, may sit comfortably at 25%. Rules of thumb do not hold. Documents do.

Getting the certificate and reading it

A serious supplier will give you an IFRA Conformity Certificate for any oil on request. If they will not, that in itself tells you something. The certificate normally contains:

• The oil's code and name — check it matches the product you actually bought.
• Which IFRA Amendment it was prepared against; the standards are revised every few years.
• A table of maximum use levels, category by category. You want row 4.
• On some certificates, an allergen list as well (the materials you must declare on the label).

Against category 4 you will see a figure like 14.2%. Do not round it up to 15 — round down. If there is no certificate and the supplier quotes a number verbally, ask for it in writing and keep it; at least then it is on record who said what.

What happens if you exceed it?

The honest answer: usually nothing, once. The risk is not a single dose of poisoning — it is cumulative. Skin sensitisation works exactly this way: a scent you wore happily for months comes back one day as redness, itching or a lasting sensitivity. And once you are sensitised, the next contact with the same material provokes a faster reaction.

The second issue is phototoxicity: some citrus components can cause pigmentation under sunlight (bergapten in bergamot is the best-known example). Limits exist for that too.

Third, if you sell what you make, the whole thing moves onto legal ground. Anything placed on the market as a cosmetic needs a product information file, a safety assessment and label declarations — and the first step of all of that is IFRA compliance. If you make it for yourself and wear it yourself, nobody is going to knock on your door; but it is still your skin.

So how do you actually pick a concentration?

Keep two separate questions apart. First, “what is the maximum allowed” — the answer is on the IFRA certificate and is not up for debate. Second, “what concentration smells right” — the answer is in your own testing.

That table is a rough map. The reality is this: if an oil's IFRA limit is 12%, you cannot push it to 20% because you “want to make an EDP.” That oil does not become an EDP. Either you accept it and stop at 12%, or you choose a different oil. Staying under the limit does not mean a weak scent either — most of the longevity comes from the structure of the oil itself and from the fixative in your base.

How will you keep track of this?

You can hold about five oils in your head. After the fifteenth it is impossible: which one was 12%, which was 25%, which code belonged to which house. A paper notebook has its own limit too, because you end up hunting for the same number every time you work out a bottle.

Our approach is simple: write the limit into the oil's own record once, then keep it in front of you on every calculation screen. If you push the concentration above it, you get a warning — but not a block. The final call belongs to the maker.