What are fragrance oils, and how do you make perfume with them?
By Omer Siton, founder of PerfuMate · Updated
A fragrance oil is a ready-made fragrance: a blend of aroma chemicals, natural materials or both, composed by a supplier and sold under a name, for candles, soap and diffusers as well as for perfume. It can become a perfume, but only if it was made for skin: check that the supplier's IFRA certificate covers Category 4, fine fragrance, then dilute it by weight in perfumer's alcohol like any perfume concentrate.
What is a fragrance oil, and what is it made of?
"Fragrance oil" is a trade name for a finished fragrance blend, not a regulated category, and the name says nothing about what is inside. The industry's own words are fragrance mixture or fragrance compound. It can be built from any of the materials perfumers use: IFRA's Transparency List, its register of the ingredients used to create fragrance mixtures, holds natural complex substances such as essential oils beside synthetic aroma chemicals, plus functional ingredients such as solvents and antioxidants.
Two things follow. Suppliers rarely publish the full formula, so the ingredient list you can get is partial: the safety data sheet names the ingredients classified as hazardous and their concentrations (in the US, OSHA requires the name and concentration of each ingredient classified as a health hazard above its cut-off, with exceptions for trade secrets), and an allergen declaration lists the EU's declarable fragrance allergens. And many fragrance oils are sold already diluted in a solvent such as DPG or isopropyl myristate, which changes how much fragrance a gram of the oil carries. Ask the supplier.
Are fragrance oils natural?
Usually not entirely, and the label rarely says. A fragrance oil may be all synthetic, all natural or a mix, and "natural" on a fragrance oil is the seller's description, so ask what it means: essential oils and extracts only, or nature-identical aroma chemicals, which are synthetic copies of molecules that also occur in plants. If you want a natural perfume, buy the naturals themselves and compose with them (how to make natural perfume). Aroma chemicals vs essential oils explains why neither side is safer by default.
Essential oils vs fragrance oils: what is the difference?
An essential oil is one natural material, distilled or expressed from one plant; a fragrance oil is a composed blend designed to smell of something, a flower, a fruit or "fresh linen", and it usually includes aroma chemicals. An essential oil is an ingredient; a fragrance oil is already a finished fragrance. Aroma chemicals are the third kind of material people compare them with:
| Essential oil | Aroma chemical | Fragrance oil | |
|---|---|---|---|
| What it is | The volatile part of one plant, a natural mixture of many molecules | One molecule, or a small set of isomers, at a known purity | A finished blend composed by a supplier |
| What decides the smell | The plant, its origin and the harvest | The molecule | The supplier's formula, which you usually cannot see |
| From batch to batch | Varies with origin and season | The same at the same purity | As consistent as the supplier makes it |
| IFRA paperwork | Typically no certificate; the supplier states conformity where a standard covers the oil itself | Counted as itself; some have a standard of their own | The supplier's IFRA certificate, category by category |
| In a perfume | One line among many | One line among many | The whole concentrate, or one line in your own formula |
Is fragrance oil the same as perfume oil, or a "fragrance oil concentrate"?
Not necessarily: a perfume oil is a perfume to wear, a concentrate diluted in a carrier oil instead of alcohol (how to make perfume oil), while a fragrance oil is the blend you make things from. "Fragrance oil concentrate", "perfume concentrate" and "perfume compound" usually mean that blend before dilution, which is what a perfumer calls the concentrate (perfume concentrations, explained). Some shops call a fragrance oil sold for wearing neat a "perfume oil", so read the product description and the IFRA certificate, not the name.
Are fragrance oils safe for skin?
Only the ones made and certified for skin, and only up to the level the certificate allows. Three documents tell you, and a supplier selling oils for perfume should have all three:
- The IFRA Certificate of Conformity. The company that makes a fragrance mixture writes it for its customers; IFRA itself creates none. It states up to what concentration the oil may be used in each IFRA product category, and for a perfume the figure that matters is Category 4, fine fragrance. An oil certified only for candles has not been cleared for skin: IFRA places candles in Category 12 and, because skin contact is negligible, does not restrict fragrance ingredients in them for sensitization, so a candle oil can legitimately hold materials at levels far over the skin limits (IFRA categories explained).
- The safety data sheet (SDS). Hazards, handling, the ingredients classified as hazardous, and physical data including the flash point.
- The allergen declaration. The EU's declarable allergens and their share of the oil, which you need for your own label (how to label a perfume for sale).
On the other words people search: whether an oil is "toxic" depends on its materials and their dose, which is what the certificate and the SDS address. For flammability, the SDS gives the oil's flash point, and once the oil is diluted in perfumer's alcohol the perfume is flammable like the alcohol, whose flash point is about 13 °C. "Phthalate-free" is about solvents such as diethyl phthalate, an old fragrance solvent that the catalog notes has largely given way in fine fragrance to DPG, isopropyl myristate and triethyl citrate. And IFRA is explicit that a certificate does not replace a safety assessment, which a perfume sold to the public needs.
How do you make perfume with a fragrance oil?
Treat it as the concentrate: check the certificate, choose a strength no higher than its Category 4 figure, and dilute it by weight in perfumer's alcohol.
- Read the Category 4 figure. It is a share of the finished perfume, and it is your ceiling. If it says 12%, you can make a perfume at 10% or 12%, but not at 18%.
- Choose the strength at or below that ceiling. The usual ranges are on the concentrations page.
- Weigh. A 30 ml bottle holds about 24 g of perfume, because alcohol weighs about 0.8 g per ml; make 25 g. At 18%: 4.5 g of fragrance oil and 20.5 g of perfumer's alcohol. With a 12% ceiling: 3 g of oil and 22 g of alcohol.
- Allow for a diluted oil. If the oil is sold at 50% in DPG, 4.5 g of it carries 2.25 g of fragrance, so the perfume is weaker than its numbers suggest. The certificate covers the product exactly as the supplier sells it.
- Rest, chill and filter. Cap it, keep it cool and dark, judge it on a strip after a week and again over the following weeks, then chill it and filter any haze (how long to macerate perfume, why a perfume turns cloudy).
Is 30% fragrance oil good for a perfume? Only if the certificate allows 30% in Category 4, and only if you want an extrait: 30% is the top of the extrait range. For a perfume oil instead of a spray, use a carrier such as jojoba oil or fractionated coconut oil in place of the alcohol; for an oil worn like a perfume the Category 4 figure still applies, because IFRA's fine fragrance category covers non-alcoholic perfumes too, while IFRA's guidance puts an oil used like a body oil in Category 5A instead. Water is no substitute for alcohol, because most perfume materials do not dissolve in it (perfume dilution).
How do I choose a good fragrance oil for perfume?
By its documents and on a strip, not by its name; no list of brands answers this honestly. A fragrance oil worth putting in a perfume:
- is sold for fine fragrance or skin, with an IFRA certificate under the amendment in force whose Category 4 figure is high enough for the strength you want;
- comes with an SDS and an EU allergen declaration;
- says whether it is neat or diluted, and in what;
- smells right over a whole day on a blotter, not only in the first minute: smell it at once, after an hour and the next morning (how to evaluate materials on blotters);
- is sold in sample sizes, so you can test it at your strength before you buy more, and smells the same when you reorder.
Oils sold only for candles or soap, or sold with no certificate at all, stay out of a perfume however good they smell. An oil sold as "inspired by" a famous perfume is judged by the same documents; the legal side of copying a perfume is on can I recreate a perfume.
Can I mix fragrance oils, or add one to my own formula?
Yes: a fragrance oil is a line like any other material, and two oils, or an oil and your own materials, make a formula. The limits then stack, because the same restricted molecule can sit in both oils. A rule that is always safe: divide each oil's share of the finished perfume by its certificate's Category 4 maximum and add the results; the total must not pass 1. Two oils certified at 20% and 10%, used at 8% and 4% of the perfume, give 0.4 plus 0.4, which is 0.8, so the blend is within. Add a material of your own and neither certificate covers the result any more: the check becomes yours. PerfuMate's IFRA calculator cannot see inside an oil it does not know: a line it cannot match stays unchecked, and the result says the formula is not fully checkable rather than calling it fine. Where PerfuMate holds a supplier's certificate for a named trade blend, that cap is applied to it.
PerfuMate's free perfume making calculator works out the grams of fragrance oil and alcohol for any bottle size and strength, in the browser and without an account.
Sources: IFRA, Certification of IFRA Standards; IFRA, About the IFRA Transparency List; IFRA, Guidance for the use of IFRA Standards (51st Amendment: candles in Category 12, fine fragrance in Category 4, oil formats by use); OSHA, Hazard Communication Standard: Safety Data Sheets; ethanol flash point from the NIOSH Pocket Guide.