How to dilute perfume oil
The oil and the alcohol for any bottle at any strength, in grams and millilitres at once — with the top, heart and base split checked as you build the blend.
INPUTS
ml
Measured in
Strength
The default for a first serious batch, and what most people mean by "perfume". Strong enough to last a working day and still comfortable to spray. Reads for 5–8 hours. These bands
are convention, not regulation — no country defines them in law.
%
Usually none. A few percent softens a sharp opening.
The standard answer, and what a craft supplier means by "perfumers alcohol". Ethanol denatured with tert-butyl alcohol and a bitterant so it cannot be drunk — which is what exempts it from beverage alcohol tax and is why it costs a fraction of the undenatured equivalent. Odourless, dries clean, holds aromatics properly.
High-proof alcohol is flammable — no naked flames, and work somewhere ventilated. Anything you blend needs
about 28 days before it is worth judging, and it will smell sharp and alcoholic for
the first two.
RESULTS
Aromatic compound
4.49 g
18.0% by weight 15.8% by volume
Weigh out
| Ingredient | Share | Amount |
|---|---|---|
| Fragrance oil (unspecified) | 100.0% | 4.49 g |
| Perfumers alcohol (SDA 40B) | 82.0% | 20.47 g |
Finished volume
30.0 ml
Finished weight
25.0 g
Weight-to-volume gap
12.4%
Ready to judge
28 days
Strength is a share of the finished perfume by weight, which is how formulae are written — so the same recipe
measured with a pipette comes out about 12.4% weaker than it reads. That is the gap above, and it is the
reason a scale beats a dropper. The compound's own shares are quoted against itself, so changing the strength
cannot quietly change the blend.
How this is worked out
A perfume is aromatic material dissolved in alcohol, and the strength is a share of the finished bottle BY WEIGHT — which is how every professional formula is written, and almost never how a home recipe is. The arithmetic runs from the bottle inwards: the compound is its percentage of the total, the alcohol is what is left. Working the other way, adding materials one at a time into a bottle of alcohol, gives a formula you cannot restate at a different strength and cannot tell anyone else how to make. The awkward part is that people buy bottles in millilitres and own pipettes rather than milligram scales, so the same calculation also runs from a finished volume back to the weights — treating volumes as additive, which is a small lie for ethanol and water and a negligible one for ethanol and oil. Because the two conventions disagree, this tool reports both: at 18% by weight the same bottle reads 15.8% by volume, a gap of about 12%. The compound's own shares are quoted against itself rather than against the bottle, so changing the strength cannot quietly change the blend you built.
aromatic = total weight × concentration concentration is by WEIGHT
alcohol = total weight − aromatic − water
from a finished volume V:
aromatic = V ÷ ( 1/sg_oil + (1 − p) ÷ (p × sg_alcohol) )
sg_alcohol = 0.81 sg_oil = 0.85–1.15 depending on the material
drops = ml × 20 an average, not a measurement
Questions makers ask
How do you dilute perfume oil?
Weigh the oil, then add alcohol until the bottle reaches its finished weight. For a 30 ml eau de parfum that is about 4.5 g of oil to 20.5 g of perfumers alcohol (sda 40b) — 4.7 ml and 25.3 ml if you are working by volume. Then it needs about 28 days to settle before it is worth an opinion.
What is the perfume oil to alcohol ratio?
It depends entirely on the strength you want, and the strength is the only thing the names mean. Eau de parfum is 15–20% oil by weight, so roughly 1 part oil to 4.5 parts alcohol. Eau de toilette is 5–15%, which is nearer 1 to 9. Extrait runs 20–40%. None of those bands is defined in law anywhere — houses set their own and disagree with each other constantly.
Is perfume concentration measured by weight or by volume?
By weight, in every professional formula, because a scale repeats and a dropper does not. This matters more than it sounds: aromatic materials are mostly denser than alcohol, so the same recipe measured with a pipette comes out about 12% weaker. A 18% eau de parfum by weight reads as 15.8% by volume. The tool above shows both figures at once, because almost no published recipe says which one it meant.
How much fragrance oil goes in a 30 ml bottle?
About 4.5 g at eau de parfum strength and 2.5 g at eau de toilette. The alcohol makes up the rest — 20.5 g and 22.2 g respectively. Nothing else is needed, and adding water to a high-strength blend is the usual cause of one that will not go clear.
How many drops of essential oil in 10 ml of perfume?
Around 32 at eau de parfum strength, taking 20 drops to the millilitre. Treat that as an estimate rather than a measurement: drop size follows viscosity, so bergamot at 0.876 g/ml and vanilla absolute at 1.1 g/ml behave very differently in the same pipette. Drops are fine for finding a blend and poor for repeating one.
Can I dilute perfume oil with vodka?
Not well. Vodka is 40% ethanol and 60% water, and most aromatic materials will not dissolve in water — so the blend hazes, separates, and the water gives it a shelf life of weeks. You want something around 95% ethanol. <a href="/where-to-buy-perfumers-alcohol">Where to buy it</a> covers the grades and why it is awkward to ship.
What is the top, heart and base split?
A convention for how a blend is layered by volatility, quoted as shares of the compound rather than of the bottle. The classic starting point is 30/50/20. Top notes read for 5–30 minutes, heart notes for 1–4 hours and base notes for 4–24 hours. The blend view above shows what your compound is actually running at against the target you picked.
Why did my perfume go cloudy?
Either water got in, or something has come out of solution — a wax, a resin fraction, or occasionally just cold. Both are fixable and neither affects the smell. If it is water, there is nothing to do but remake it with a higher-proof alcohol. If it is a material dropping out, freezing the bottle and filtering it cold clears it permanently. <a href="/perfume-maceration">The maceration guide</a> covers the whole procedure.
Read before your next batch
- Make your own perfume Blend the compound, dilute it into alcohol, then leave it alone for a month. Everything else is detail — and this page has the detail.
- Where to buy perfumers alcohol It is cheap, it is not restricted, and it is still the hardest thing in this craft to get hold of. Here is why, and what to ask for.
- Perfume maceration: how long to age a perfume Maceration is the word for leaving it alone. It is also the difference between a blend and a perfume, and it is the step nearly everyone skips.
- Perfume notes explained: top, heart and base Notes are not ingredient categories. They describe how fast something leaves your skin — and that one fact explains everything else about the pyramid.